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Aug 172012
 
raven

© 2003 Joyce Gross

What is it?

West Nile Virus is a potentially serious illness, with approximately 1 in 150 infected individuals developing WNV meningitis or encephalitis. Although the Centers for Disease Control estimates that four in five infected people will show no signs at all, severe symptoms can include high fever, headache, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, vision loss, numbness, and paralysis. Among milder symptoms are fever, headache, body aches, nausea, vomiting, and sometimes swollen lymph glands or a skin rash on the chest, stomach, and back.

How is it spread?

Although humans can feasibly spread the disease among one another through blood transfusions, organ transplants, breastfeeding, and even between mother and fetus, WNV is typically transmitted from infected birds to humans via disease-carrying mosquitoes. Hundreds of species of birds can be infected with WNV.

finch

Dr. Lloyd Glenn Ingles © California Academy of Sciences

What steps can you take in your garden to minimize your risk?

According to the National Audubon Society, the best way to reduce the presence of WNV in your neighborhood is to keep mosquitoes from breeding in your yard:

  • Discard old tires and aluminum cans and drill drainage holes in the bottoms of items in which water collects.
  • Prevent water from accumulating in flowerpots or barrels and on swimming pool and boat covers.
  • Change the water in birdbaths and pet dishes at least every 3-4 days (some experts recommend every 48 hours).
  • Clean roof gutters, clean and chlorinate swimming pools, and turn over wheelbarrows and plastic wading pools when you’re not using them.
  • Aerate ornamental pools or stock them with mosquito-eating fish.
  • Fill water-collecting tree cavities with soil or sand.
  • Alter your landscaping to eliminate standing water.

For more information on WNV, visit:

 August 17, 2012
Aug 172012
 
water can

Water is key to container plant health

Principles for maintaining healthy plants in containers are no different than for plants in a garden. However, in practice, container plants require greater attention to detail. Limited soil volume and potential stress create requirements for frequent irrigation and fertilizer and constant monitoring for pests.

Irrigation

There is no easy way to schedule watering of container plants. During hot weather, irrigation may be needed every day. However, it should be recognized that overwatering of container plants is a more common cause of death than is underwatering. With that said, a rule of thumb is to let the top 1-2 inches of soil completely dry between irrigations. When applying water, add a sufficient quantity to allow some water to drain out the bottom of the pot.

Fertilization

A high level of fertility must be constantly maintained in containers to keep plants healthy and attractive. The two best methods for applying fertilizer are to 1) mix a slow-release granular fertilizer into the top few inches of soil in the spring and again in mid-summer, or 2) use a solution of a complete fertilizer once a week when irrigating the containers.

Pest Control

Many insect pests infest container plants to a greater degree than garden-grown plants, especially spider mites. Diseases also can become problematic, especially if plants are stressed. Plants should be monitored frequently to identify pest problems before damage becomes severe. Pest control methods for container plants are identical to those described in the other places in this web site (annuals, perennials, bulbs, Insect and Disease Pests).

Excellent information on container gardening is provided Chapter 19 of the Idaho Master Gardener Handbook.

Kansas State University provides detailed container garden instruction.

 August 17, 2012
Aug 172012
 

Once established, ornamental grasses tend to be relatively carefree. In general, they require little in the way of fertilizer and water inputs. However, as is true of all plants, some tender loving care is needed to keep them healthy and attractive.

Mulching

If not done before planting, it is beneficial to mulch around ornamental grasses. This will keep the soil cool, retain moisture, and help with weed control.

hose running

Ornamental grasses need minimal water

Irrigation

Ornamental grasses, in general, should be irrigated less often and to a greater depth than other parts of the landscape. Some fescues and other drought tolerant grasses may need much less water overall. During July and August, a weekly irrigation with about 2 in. of water should be adequate in most soils. In sandy soils, less water should be applied on a more frequent basis. The amount of water applied should be cut back during the cooler spring months, the late fall, and during those infrequent periods of rain.

Fertilization

Most ornamental grasses need very little in the way of fertilizer. They may benefit from a spring application of a fertilizer high in nitrogen at the equivalent of 1-3 lbs nitrogen per 1,000 sq. ft. On the other hand, some years, no fertilizer of any kind may be needed. Determination of requirement is based on growth response. If the previous year, plants were slow growing, small, with yellow color, add some fertilizer.

shears

Grasses can be cut back in fall or winter

Manicuring

The only consistent need for ornamental grasses is removal of dead leaves and flower spikes at the end of the season. For many species, those that break, shatter, or fall over in the winter, this should be done in late fall. For grasses that remain attractive through the winter, this can be done in early spring. Cut grasses back to a height of 4-5 inches before new growth appears.

Weed Control

There are no options to completely replace hand weeding in ornamental grasses. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Perennial weeds that creep into beds create the most difficult problems. If hand cultivation provides inadequate control, it may be necessary to hand apply a herbicide, such as a glyphosate product, by hand with a sponge or other wicking material.

Icy grass

Grasses may benefit from winter protection

Winter Protection

Most adapted ornamental grasses can withstand winters without winter protection. However, a layer of mulch over the crown may allow the plants to be more vigorous in the spring. Proper winter mulching consists of application of 3-4 inches of compost, leaves, wood chips, or other organic matter. The mulch should be removed from around the crowns in early spring to help prevent premature growth of shoots that may be damaged by frost.

For more information on the general care of ornamental grasses, see the following two web sites:

Disease and Insect Control

Ornamental grasses have very few consistent pest problems. However, there are a few organisms that can infest grasses and make them less attractive. Some of these are listed below. For detailed information on control of these insects and diseases, as well as information on other pests, see the Insect and Disease Pests section of this site.

Insect Problems

Mealybugs: Are sucking insects, one species of which can become a problem on the Miscanthus grasses. Mealybugs are easily recognized by the presence of a cotton-like white substance they deposit for protection. In cases of serious infestation, the plants will be stunted and go dormant earlier than healthy plants.

Control of mealybugs can be had by spraying the plants with a direct stream of water, using and insecticidal soap, or using a registered insecticide.

snail

Snails often live in the crowns of grasses

Slugs and Snails: Prefer damp soil and humid conditions. Slugs and snails often hide during the day and feed at night. Symptoms include chewed leafs and glistening slime trails on plant surfaces. Although slugs and snails will not do significant damage to most ornamental grasses, the thick foliage may provide a haven from which they will emerge and damage surrounding plants.

Control snails and slugs with baits.

Disease Problems

Leaf Rusts: Are caused by several related fungal pathogens that penetrate and kill leaf tissue. Symptoms are usually typified by a yellow, orange, or brownish discoloration of the upper leaf surface on older leaves. The leaves eventually decline and die. These diseases are usually worse following a wet spring.

Removal of all dead plant material at the end of the growing season helps prevent many leaf spot diseases in subsequent years. In-season control usually requires use of a registered fungicide. Maintaining overall plant health is important in controlling fungal leaf diseases. Ensuring proper aeration among plants will reduce humidity and slow the progress of rusts.

 August 17, 2012
Aug 172012
 

Bulbs do not require and excessive amount of care, but timing and quantity of inputs are unique relative to other perennials. Here is a guide to care for established bulb gardens.

Mulching

If not done before planting, it is beneficial to mulch the bulb flower bed before heat of summer sets in. This will keep the soil cool, retain moisture, and help with weed control.

Hose

Bulbs require deep watering

Irrigation

Bulbs have a range of water needs, depending on species, but most need soil that is consistently moist. For spring bulbs, except in the case of a very dry spring, irrigation is not usually needed until about the time flower buds appear on the plants. Once started, irrigation will likely be needed until the foliage dies and the bulbs go dormant. Because they are planted deep, bulbs should be irrigated less often and to a greater depth than nearby lawn areas. Summer flowering bulbs will likely need water until first frost.

Fertilization

Bulbs are not considered heavy feeders, but do need an annual application of fertilizer to look their best. Use a complete fertilizer that is relatively high in phosphorus. Apply the equivalent of 2-3 lb nitrogen per 1,000 sq.ft. Timing of application is fairly critical. Bulbs begin growing new roots very early in the spring and need fertility available to start this process. So, the best time to apply fertilizer to spring bulbs is in October or early November. A second option is to apply half the fertilizer in the fall and the other half about the time the plants begin to flower. Summer blooming bulbs do best with fertilizer applied about the time the plants emerge or when they are transplanted outside.

Weed Control

There are no options to completely replace hand weeding in bulbs. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Perennial weeds that emerge before the bulbs can be sprayed out with a glyphosate product. Grasses in irises and gladiolas can be controlled with a grass herbicide containing sethoxydim. Grass controlling herbicides cannot be used on other bulbs without risk of serious injury.

Staking

Some bulb plants, especially summer bulbs, have large flowers and somewhat weak stems. They may need to be tied to stakes or allowed to grow inside a support cage to remain upright and attractive.

Pruners

Foliage should die naturally before pruning

Post-bloom Care

Immediately after the bloom period, all seed heads should be removed. This not only improves appearance, but allows the plant to direct its energy to producing new and larger bulbs. The foliage of bulb plants should be allowed to die naturally (or at least be yellow and dying before removal). Healthy leaves are essential to the process of growing new bulbs. Over a period of a few years, removing the leaves too early will cause the bulbs to become smaller and decline in vigor.

Many gardeners do not like the look of post-bloom foliage in the garden. The unattractive leaves can be masked by planting other types of flowers in the bulb garden that will take up the slack in bloom time while the bulbs complete their growth and decline.

Over a period of several years, some bulb plants, such as daffodils, tulips, and crocuses will produce many bulbs and become crowded. When severe, this crowding will reduce bloom potential and make blooms smaller. This can be solved by uncovering the bulbs, dividing them into single units, and replanting the largest and healthiest of the bulbs at a more appropriate spacing. Dividing is best done in the fall, the usual time for planting bulbs. However, by fall all sign of foliage is gone and it is hard to identify the location of the bulbs. This can be solved by using small stakes to mark the plants before they die, or as a second best option, by simply dividing in late spring when the foliage has declined but still marks the presence of plants. Bulbs that are freshly dug and divided should be replanted as quickly as possible to prevent damage from drying conditions. Although not considered an option of choice in Idaho , spring bulbs can be harvested after blooming and stored in the refrigerator until being replanted in the fall.

Tender summer bulbs

Tender summer bulbs must be harvested and stored in the fall

In all regions of Idaho , the tender summer bulbs, such as dahlia, canna, tuberous begonia, and gladiolas must be harvested at the end of the growing season and stored indoors. Otherwise, the bulbs will be damaged or killed by freezing soil conditions. At the first sign of frost injury on the foliage, the bulbs should be harvested, cleaned, cured, and stored. Proper storage conditions vary by species. Complete discussion of the harvesting and storing process, including proper storage conditions for common summer bulb plants, can be found in a University of Minnesota document written by Mary Meyer.

The University of Illinois provides more general information on growing bulbs.

Forcing Bulbs

The term forcing refers to growing practices that bring bulb flowers into bloom during the off-season. Typically, this process is used to produce indoor flowers during the winter months. For each species, certain environmental constraints must be met to overcome bulb dormancy and allow growth and bloom. For spring bulbs, this usually means cold storage before planting in a pot. For summer bulbs, it may mean supplying specific requirements of light duration. It is beyond the scope of this discussion to provide specific requirements of all plants, but understand it can be done and seek procedures elsewhere. Information on forcing spring bulbs can be found on the University of Kentucky site.

Insect and Disease Control

It is beyond the scope of this site to provide specific pest management information for the large number of commercially available bulb species. Each has unique problems that may be more or less serious. However, there are many pests that are common and infest many types of plants. Diagnostic and simple control information will be given below for these common pests. For detailed information on control of insects and diseases, as well as information of other pests, see the Insect and Disease Pests section of this site.

Insect Problems

Aphids: Also known as plant lice. Small, soft-bodied, sucking insects that cluster on the stems or underside of leaves. Aphids are usually wingless and green, brown, or black in color. Symptoms of infested plants include distorted or curled leaves, presence of sticky sap (honeydew) on the infested surfaces, and misshapen new growth.

Aphids can be controlled with the use of insecticidal soap or a registered insecticide. A strong stream of water directed at the infected plants may knock them from the plant. Many beneficial insects feed on aphids and if an infestation is not too severe, it may be appropriate to be patient and let nature take its course.

Spider Mites: Not actually insects, these miniscule pests are actually related to spiders. They spin protective webs on the underside of leaves and feed by sucking juice from the leaves. Symptoms include color mottling that, at a distance, may appear as a general yellowing of older leaves. Webbing will be presence on the underside of infested leaves. The mites, to small to be easily visible, can be detected by shaking a leaf over piece of clean white paper.

Spider mites prefer dry, dusty environments. Sprinkler irrigation or routine washing of leaves with water usually keep them at bay. A severe infestation may require the use of a registered miticide. Most common insecticides are ineffective against spider mites.

slug

Slugs can damage many bulb flowers

Slugs and Snails: Prefer damp soil and humid conditions. Slugs and snails often hide during the day and feed at night. Symptoms include chewed leafs and glistening slime trails on plant surfaces.

Control snails and slugs with baits.

Thrips: Damage is cause by the larva of this small, four-winged insect. Thrips reside on the underside of leaves and use their rasping mouthparts to scrape away the surface of the leaf after which they feed on the sap. Symptoms appear as white streaks and blotches, more prominent on the underside of the leaf.

A light infestation does little permanent damage to the plant and can be ignored. A heavy infestation will likely require the use of a registered insecticide.

Disease Problems

Root and Bulb Rots: Are caused by the penicillium (blue mold) and Fusarium fungi and the soft rot bacteria that live in the soil. These organisms are worse problems on bulbs that are harvested and stored than on those that are left in the soil over winter. Infected bulbs become soft, pink, or mushy and often have an offensive odor.

Control measures include careful harvesting to prevent injury that provides a point of entry for rot organisms. Infected bulbs should immediately be eliminated.

grey mold on peonies

Grey Mold affects many bulb plants, including peony

Grey Mold or Botrytis: Is caused by a fungus that overwinters in the soil. It infects plant stems that touch moist soil surfaces and splashed onto leafs with rain or irrigation water. Symptoms include water-soaked spots on the leaves that become a slimy, grey mold. Infected tissue quickly collapses and dies.

Control includes removal of infected tissue, both live and dead. In severe cases it may be necessary to apply a preventative fungicide.

Daffodils with virus

Bulb can be affected by chronic viruses

Virus: Not technically alive, viruses are small, disruptive pieces of genetic material that disrupt plant function. Symptoms vary widely and usually include some combination of stunting, yellowing, mottling, or leaf and stem distortion. Viruses are a particularly severe problem on bulbs and other perennials because their long life span and lack of seed propagation create many opportunities for chronic infection.

There are no control measures for viruses other than using resistant varieties or controlling the organisms (usually insects) that transfer them from one plant to another. Prevention involves removing and destroying any infected plants.

Information on control of garden insects and diseases common to Idaho can be found in the online Idaho Master Gardener Handbook.

See specific information on controlling bulb diseases and insects at the University of Connecticut web site.

 

Ornamental onions

Ornamental onions are eye-catching summer bulbs

 August 17, 2012
Aug 172012
 

Once established, most perennial plants are relatively carefree. In general, they require less in the way of fertilizer and water inputs than do annuals. However, as is true of all plants, some tender loving care is needed to keep them healthy and attractive.

wood chips for mulching

Wood chips as a mulch layer

Mulching

If not done before planting, it is beneficial to mulch the flower bed before heat of summer sets in. This will keep the soil cool, retain moisture, and help with weed control.

Irrigation

Perennial plants should be irrigated less often and to a greater depth than nearby lawn areas. Many perennial plants have effective rooting depths of up to three feet. During July and August, a weekly irrigation with about 2 in. of water should be adequate in most soils. In sandy soils, less water should be applied on a more frequent basis. The amount of water applied should be cut back during the cooler spring months, the late fall, and during those infrequent periods of rain. A few perennials are adapted to very moist or even saturated soil conditions. These must be watered more often.

Fertilization

Most perennial plants need very little in the way of fertilizer. They may benefit from a spring application of a fertilizer high in nitrogen at the equivalent of 1-3 lbs nitrogen per 1,000 sq. ft. On the other hand, some years, no fertilizer of any kind may be needed. Determination of requirement is based on growth response of the plants. If the previous year, plants were slow growing, small, or yellow in color, add fertilizer at the higher end of the recommendation. If they were growing well and looking nice, add at the low end of the recommendation. If they were vigorous, floppy, and too large, do not add any fertilizer.

seed head

Removing old seed heads will aid flowering

Manicuring

Although relatively carefree, some perennials need attention to remain attractive throughout the summer. Plants that look thin and leggy can be forced to produce more lateral growth by shearing or pinching off the growing point of each stem. Plants that have many stems may produce bigger stems and larger flowers if some of the stems are pruned out. Removing lateral flower buds, leaving only the top-most bud, will also make flowers larger. Plants that fall down or become floppy may need to be staked or interplanted with stiffer, more upright types of plants. Deadheading will prolong flowering of many perennials and make the plants more attractive.

Weed Control

There are no options to completely replace hand weeding in annuals. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Perennial weeds that creep into beds create the most difficult problems. If hand cultivation provides inadequate control, it may be necessary to hand apply a herbicide, such as a glyphosate product, by hand with a sponge or other wicking material.

Perennials may require winter protection

Perennials may require winter protection

Winter Protection

In the fall, perennials (except those that provide some winter interest or seedheads for sustaining birds and other wildlife) should be cut back to a height of 3-4 inches. This will create a more attractive winter landscape and allow the crowns to be covered with a layer of mulch. Proper winter mulching consists of application of 3-4 inches of compost, leaves, wood chips, or other organic matter. The mulch should be removed from around the crowns in early spring to help prevent premature growth of shoots that may be damaged by frost and rot in wet spring climates.

Disease and Insect Control

It is beyond the scope of this site to provide specific pest management information for the large number of commercially available perennial species. Each has unique problems that may be more or less serious. However, there are many pests that are common and infest many types of plants. Diagnostic and simple control information will be given for these common pests in our sections on insects and disease problems. For detailed information on control of insects and diseases, as well as information of other pests, see the Insect and Disease Pests section of this site.

Aphids with a predatory lady bug larvae ©2004 Cornell Plant Pathology Herbarium

Aphids with a predatory lady bug larvae ©2004 Cornell Plant Pathology Herbarium

Insect Problems

Aphids: Also known as plant lice. Small, soft-bodied, sucking insects that cluster on the stems or underside of leaves. Aphids are usually wingless and green, brown, or black in color. Symptoms of infested plants include distorted or curled leaves, presence of sticky sap (honeydew) on the infested surfaces, and misshapen new growth.

Aphids can be controlled with the use of insecticidal soap or a registered insecticide. A strong stream of water directed at the infected plants may knock them from the plant. Many beneficial insects feed on aphids and if an infestation is not too severe, it may be appropriate to be patient and let nature take its course.

Caterpillars can be destructive

Caterpillars can be destructive

Caterpillars: Are the larvae of numerous species of moths and butterflies. These voracious legged worms come in many sizes and colors. Plant symptoms include chewed or completely missing leaves. Some types of caterpillars will roll or fold the leaves and hide inside. Often, frass or droppings are present on and around the plants.

A light infestation can be easily controlled by picking them from the plant a crushing them. Common registered insecticides will effectively kill caterpillars.

Leafminers: Are small insect larvae that burrow under the leaf surface while feeding. Symptoms are easily recognized and exhibit themselves as zig-zag or wandering lines on the upper leaf surface that are lighter in color that the rest of the leaf surface. These are tunnels in the leaves caused by leafminer feeding.

A light infestation of leafminers can be controlled by removing and destroying damaged leaves. A heavy infestation will require the use of a registered systemic type insecticide.

Mealybugs: Are sucking insects that infest stems of many plants. Mealybugs are easily recognized by the presence of a cotton-like white substance they deposit for protection.

Control of mealybugs can be had by spraying the plants with a direct stream of water, using and insecticidal soap, or using a registered insecticide.

Spider Mites: Not actually insects, these miniscule pests are actually related to spiders. They spin protective webs on the underside of leaves and feed by sucking juice from the leaves. Symptoms include color mottling that, at a distance, may appear as a general yellowing of older leaves. Webbing will be presence on the underside of infested leaves. The mites, to small to be easily visible, can be detected by shaking a leaf over piece of clean white paper.

Spider mites prefer dry, dusty environments. Sprinkler irrigation or routine washing of leaves with water usually keep them at bay. A severe infestation may require the use of a registered miticide. Most common insecticides are ineffective against spider mites.

Slugs and Snails: Prefer damp soil and humid conditions. Slugs and snails often hide during the day and feed at night. Symptoms include chewed leafs and glistening slime trails on plant surfaces.

Control snails and slugs with baits.

Thrips: Damage is cause by the larva of this small, four-winged insect. Thrips reside on the underside of leaves and use their rasping mouthparts to scrape away the surface of the leaf after which they feed on the sap. Symptoms appear as white streaks and blotches, more prominent on the underside of the leaf.

A light infestation does little permanent damage to the plant and can be ignored. A heavy infestation will likely require the use of a registered insecticide.

Whiteflies: In Idaho are more commonly a problem in greenhouses than they are outdoors. They are small insects with distinct bright white wings that reside and feed on the underside of leaves. Symptoms include the presence of honeydew on leaf surfaces, often accompanied by a lack sooty mold. When disturbed, clouds of the white, rapidly flying insects will rise above the foliage, then quickly resettle.

Trap the flies with yellow sticky boards or use a registered insecticide.

Disease Problems

Damping Off: Caused by fungal pathogens that infect seedlings at soil level, girdling the stems and causing death. Infected seedling will develop tan-colored, soft tissue at the base of the stem. The plants fall over and usually die. Once established and actively growing, plants seldom are affected by damping off.

Control measures include maintaining optimum soil moisture and planting into well-drained soils that are not overly wet. In extreme cases, a soil drench of a registered fungicide can be applied to the soil surface. However, by the time damage is observed it may be too late for control using fungicides.

Leaf Spots: Are caused by numerous fungal (occasionally bacterial) pathogens that penetrate and kill leaf tissue. Symptoms usually start and are worse on older leaves. These diseases are usually worse following periods of wet weather and high humidity.

Removal of all dead plant material at the end of the growing season helps prevent many leaf spot diseases the following year. In-season control usually requires use of a registered fungicide.

Powdery mildew on a perennial plant © 2004 Cornell Plant Pathology Herbarium

Powdery mildew on a perennial plant © 2004 Cornell Plant Pathology Herbarium

Powdery Mildew: Is caused by fungal pathogens. The classic symptom is a whitish, powdery growth present on leaf surfaces. Heavy infections cause distortions on new growth. Infections are often worse during summers that follow damp spring weather. Plants grown in shade are more prone to infection with powdery mildew

Prevention involved growing plants in a sunny location and making sure there is plenty of space and air movement around plants. Control usually requires the use of a registered fungicide.

Root and Stem Rots: Are caused by fungi (occasionally bacteria) that live in the soil. Infected plants initially develop mild wilting symptoms that become progressively worse and may eventually cause death.

Soil pathogens are difficult to control. They can best be prevented by planting resistant varieties, avoiding overly wet soil conditions, and destroying infected plants.

White Mold: Is caused by a fungus that overwinters in the soil. It infects plant stems that touch moist soil surfaces. Symptoms include a slimy, white mold that girdles and collapses the infected tissue. Leaves above the girdled stem wilt and die. In advanced stages, small gray structures that look like mouse droppings form inside a hollowed stem.

Prevention is the best strategy and involves staking stems off the ground, spacing plants to allow air movement around foliage, and irrigating infrequently to allow intermittent drying of the soil surface.

Virus: Not technically alive, viruses are small, disruptive pieces of genetic material that disrupt plant function. Symptoms vary widely and usually include some combination of stunting, yellowing, mottling, or leaf and stem distortion. Viruses are a particularly severe problem on perennials because their long life span and lack of seed propagation create many opportunities for chronic infection.

There are not control measures for viruses other than using resistant varieties or controlling the organisms (usually insects) that transfer them from one plant to another. Prevention involves removing and destroying any infected plants.

Information on control of garden insects and diseases common to Idaho can be found in the online Idaho Master Gardener Handbook.

Diagnosis information and specific control measures for diseases in the landscape is available from the University of Kentucky.

The University of Illinois Extension has published a bulletin on control of common insect pests in flower gardens.

 August 17, 2012
Aug 162012
 

Once established, many annual plants are relatively carefree. However, as is true of all plants, some tender loving care is needed to keep them healthy and attractive.

mulch

Mulch provides many benefits

Mulching

If not done before planting, it is beneficial to mulch the flower bed before heat of summer sets in. This will keep the soil cool, retain moisture, and help with weed control.

Irrigation

Annual flowers use about the same amount of water as does lawn, equal to about ¼ in. per day during July and August. In most Idaho soils, this means approximately 1 in. of water should be applied every 4 to 5 days. In sandy soils, less water should be applied on a more frequent basis. The amount of water applied should be cut back during the cooler spring months, the late fall, and during those infrequent periods of rain. The simplest method of judging water need is to wait between irrigations for the top 1-2 in. of soil to dry.

Fertilization

In most loam soils, preplant fertilization may be adequate to provide basic nutrient needs for annual plants. However, under conditions of sandy soils or long growing season, there may be benefit in adding a small amount (equivalent of 2-3 lb nitrogen per 1000 sq. ft.) of a fertilizer that is high in nitrogen. Sprinkle the fertilizer on the soil surface and water it in. Make the application in late June or about the time the flowers reach peak bloom.

Manicuring

Some annuals need a little attention to appearance to remain attractive. Plants that look thin and leggy can be forced to produce more lateral growth by shearing or pinching off the growing point of each stem. Plants that fall down or become floppy may need to be staked or interplanted with stiffer, more upright types of plants. Many annuals either do not shed dead flowers or produce seed heads, thus reducing production of additional flowers and making the plants less attractive as the summer progresses. This can be solved by occasionally removing the dead flowers, a practice called “deadheading”.

seed head

Removing old seed heads encourages flowering

Weed Control

There are no control options that completely replace hand weeding in annuals. Mulching with organic matter or weed barriers will help by blocking germination and growth of weed seed. Some partially effective herbicides are available to help with weed control in annuals. All of these must be applied after the flowers emerge or are transplanted, but before the weeds emerge. See your county agent or local nurseryman for information on products available.

Disease and Insect Control

With over a hundred species of annual flowers commonly available, it is beyond the scope of this site to provide specific pest management information for each one. However, there are many pests that are common and infest many types of plants. We have compiled information on the most common of these in our pages on insect and disease problems.

For more detail on control of insects and diseases, as well as information of other pests not covered in the sections above, see the Insect and Disease Pests section of this site.

 August 16, 2012
Aug 162012
 
Damping off

Damping off disease of seedlings © 2004 Cornell Plant Pathology Herbarium

Damping Off

Damping off is caused by fungal pathogens that infect seedlings at soil level, girdling the stems and causing death. Infected seedling will develop tan-colored, soft tissue at the base of the stem. The plants fall over and usually die. Once established and actively growing, plants are seldom affected by damping off. Control measures include maintaining optimum soil moisture and planting into well-drained soils that are not overly wet. Maintaining air circulation is important. In extreme cases, a soil drench of a registered fungicide can be applied to the soil surface. However, by the time damage is observed it may be too late for effective control.

Leaf Spots

Leaf spots are caused by numerous fungal (occasionally bacterial) pathogens that penetrate and kill leaf tissue. Symptoms usually start and are worse on older leaves. These diseases are usually worse following periods of wet weather and high humidity.

Removal of all dead plant material at the end of the growing season helps prevent many leaf spot diseases the following year. In-season control usually requires use of a registered fungicide.

Powdery Mildew

Powdery mildew is caused by fungal pathogens. The classic symptom is a whitish, powdery growth present on leaf surfaces. Heavy infections cause distortions on new growth. Infections are often worse during summers preceded by damp spring weather. Plants grown in shade are more prone to infection with powdery mildew

Prevention involves growing plants in a sunny location and making sure there is plenty of space and air movement around plants. Control of severe infections may require the use of a registered fungicide.

Root and Stem Rots

Root and stem rots are caused by fungi (occasionally bacteria) that live in the soil. Infected plants initially develop mild wilting symptoms that become progressively worse and may eventually cause death.

Soil pathogens are difficult to control. They can best be prevented by planting resistant varieties, avoiding overly wet soil conditions, and destroying infected plants.

White Mold

White mold is caused by a fungus that overwinters in the soil. It infects plant stems that touch moist soil surfaces. Symptoms include a slimy, white mold that girdles and collapses the infected tissue. Leaves above the girdled stem wilt and die. In advanced stages, small gray structures that look like mouse droppings form inside a hollowed stem.

Prevention is the best strategy and involves staking stems off the ground, spacing plants to allow air movement around foliage, and irrigating infrequently to allow intermittent drying of the soil surface.

Virus

Not technically alive, viruses are small pieces of genetic material that disrupt plant function. Symptoms vary widely and usually include some combination of stunting, yellowing, mottling, or leaf and stem distortion.

Consistently effective control measures for viruses are rare. The best methods include using resistant varieties or preventing the infestation of organisms (usually insects) that transfer the viruses from one plant to another. Prevention also involves removing and destroying any infected plants.

For a more complete discussion of care for annual flowers, including selection, planting, general management, and pest control, see chapter 19 of the Idaho Master Gardener Handbook.

Additional information on insect and disease management in annuals is provided in this list of publications from the University of Georgia.

Diagnosis information and specific control measures for diseases in the landscape is available from the University of Kentucky.

 August 16, 2012
Aug 162012
 

Home lawns in southern Idaho are generally not faced with many disease problems because of the dry climate. Improper fertility or irrigation practices are generally the main cause of disease problems. Cool, overcast weather conditions or areas in a lawn with excessive shade also can contribute to disease outbreaks. Generally, however, a properly managed lawn will be resistant to severe disease outbreaks.

Powdery mildew

Shady areas with Kentucky bluegrass are especially susceptible to powdery mildew. Powdery mildew appears as a white, powdery mass on grass blades and large affected areas appear as if they have been dusted with flour or talcum powder. It is favored by cool, humid, shady conditions and may even appear after cloudy weather. Poor air circulation and heavy fertilization worsen the problem.

white powdery mildew on kentucky bluegrass

Kentucky bluegrass growing on the north side of a building. Note that the thin stand and white powdery mildew on the leaves closest to the wall. (Photo: T.A. Salaiz, Univeristy of Idaho)

Control. If trees are causing the shade and if possible, trim trees to minimize shade and improve air circulation. Powdery mildew is rarely serious enough to warrant control with fungicides. Overseed shady areas with shade tolerant grasses such as fine fescues or tall fescue.

Additional close up pictures and disease descriptions can be found at www.ipm.iastate.edu/

Rust

Rust is an orange colored fungus that affects the grass blades. Heavily infested lawns will leave a rust-colored dust on shoes and clothing. Rust is usually a result of under fertilized and/or drought stressed turf, and the disease is favored by cloudy, overcast conditions. Light, frequent watering will keep leaf blades wet and also increase the development of rust.

Control. Generally, good fertilization and watering practices will prevent rust from occurring. Preventative fungicides are available, but generally not warranted for home lawns.

Fairy ring

Dark circles or partial circles of lush green grass in a lawn are caused by mushroom type fungi living in the soil. These dark circles of grass are commonly referred to as fairy rings. Sometimes mushrooms will appear following wet, humid weather. In severe cases, a ring of dead grass will appear inside the ring of green grass.

The fungus that causes fairy ring grows on organic matter buried in the soil. As the fungus breaks down organic matter, nitrogen is released causing the green lush growth. In some cases, the growth of the fungus is so thick in the soil that water cannot penetrate, causing the grass to become drought stressed and die.

Control. Prevention of fairy ring involves removal of tree stumps and other wood materials from a lawn site prior to establishment. If fairy ring still appears, it can be very difficult to remove the fungus entirely. Core aeration and hand watering the affected area will help move water into the affected soil and help introduce other microorganisms that will compete with the fungus. Make sure to clean aeration equipment to avoid introducing the fungus to other areas of the lawn. Proper fertility and watering practices will help reduce the severity of the symptoms and in some cases prevent fairy ring from developing. Fungicide drenches have shown irregular success and are generally not recommended for home lawns. Severe fairy rings with large areas of dead grass may warrant removal of grass and soil from the rings followed by introducing new soil and re-seeding the area.

 August 16, 2012
Aug 132012
 

Apple Scab
Anthracnose Leaf Blight of Shade Trees
Azalea Leaf Gall Causes Crusty Leaves on Your Azalea
Bacterial Crown Gall on Ornamentals in the Landscape
Black Knot
Cercospora Blight
Control of Phytophthora and Other Major Diseases of Ericaceous Plants
Cytospora Canker of Spruce
Diseases of Ground Cover Plants
Gray Mold
Leaf Blight of Hawthorn
Leaf Diseases on Ornamental Trees and Shrubs
Life Cycle and Symptoms of Dutch Elm Disease
Oak Wilt
Pestalotiopsis Blight
Phomopsis and Kabatina Tip Blights of Junipers
Pine Cankers and Dieback
Pine Wilt
Pine Diseases Chart
Plant Disease-Resistant Apple Varieties
Plant These Disease-Resistant Roses, Tested in PNW
Powdery Mildews on Ornamental Plants
Rhizosphaera Needlecast on Spruce
Verticillium Wilt

 August 13, 2012
Aug 132012
 
University of Idaho

Insects

Encouraging Beneficial Insects in Your Garden
2001 PNW 550 Price: $1.00 (available in hardcopy only)

Honeysuckle Witches’ Broom Aphid
1992 CIS 956 Price: $0.75 (available in hardcopy only)

Locust Borer, The
1988 CIS 829 Price: $0.25 (available in hardcopy only)

Diseases

Bacterial Wetwood and Slime Flux of Trees
1990 CIS 876 Price: $0.25 (available in hardcopy only)

Cytospora Canker Disease in Idaho Orchards
1984 CIS 726 Price: $0.25 (available in hardcopy only)

Diplodia Tip Blight on Ponderosa Pine
1992 CIS 946 Price: $0.50 (available in hardcopy only)

Phytophthora Collar-Rot of Orchard Trees
1985 CIS 752 Price: $0.50 (available in hardcopy only)

Management of White Pine Weevil in Spruce

Physiological

Controlling Iron Deficiency in Plants in Idaho

Controlling Sunscald on Trees and Shrubs
1990 CIS 869 Price: $0.25 (available in hardcopy only)

Nutrient Disorders in Tree Fruits

General

Why Home Fruit Trees Die
1986 CIS 776 Price: $0.25 (available in hardcopy only)

University of Illinois

Cytospora Canker of Spruce
Needle Cast of Spruce
Spruce Spider Mite
Sphaeropsis (Diplodia) Blight

Pine Wilt
Pine Diseases Chart
Phomopsis Blight of Juniper

Cedar Rust Diseases
Phomopsis Tip Blight
Kabatina Tip Blight
Cercospora Blight
Pestalotiopsis Blight
Bagworm
Scale
European Pine Shoot Moth & Nantucket Pine Tip Moth
Zimmerman Pine Moth
Yellow Belly Sapsucker
Pine Bark Adelgids
Pine Needle Scale
Pine Tortoise Scale
Pales Weevil, Root Collar Weevil, Root Collar Weevil
Pitch Mass Borer
Gypsy Moth
Spruce Mite
Spruce Gall Adelgids
Spruce Needle Miners
Spruce Bud Scale
Anthracnose
Apple Scab
Black Knot
Cedar Apple Rust
Cedar Hawthorn Rust
Cedar Quince Rust
Chlorosis
Crown Gall
Gray Mold
Oak Wilt
Powdery Mildew
Verticillium Wilt

Ohio State University

Anthracnose Leaf Blight of Shade Trees
Cedar Rust Diseases of Ornamental Plants
Control of Phytophthora and Other Major Diseases of Ericaceous Plants
Cytospora Canker of Spruce
Diseases of Ground Cover Plants
Disorders of Yew (Taxus) in Ohio
Girdling Roots — A Problem of Shade Trees
Leaf Diseases on Ornamental Trees and Shrubs
Oak Wilt
Powdery Mildews on Ornamental Plants
Rhizosphaera Needlecast on Spruce
Root Problems on Plants in the Garden and Landscape
Sooty Molds on Trees and Shrubs
Verticillium Wilt of Landscape Trees and Shrubs
Yellowing, Dieback and Death of Narrow-Leafed Evergreens

University of Vermont
Pest Management
University of Massachusetts

Helping Trees Recover from Stress

University of Minnesota

Garden: Trees & Shrubs – Insects/Diseases

Ohio State University

plantfacts.osu.edu/faq/
http://ohioline.osu.edu/hyg-fact/3000/3304.html
http://ohioline.osu.edu/b614/index.html

 August 13, 2012
Aug 132012
 

Plant Problem (Symptoms) Pathogen Insect Physiological Notes
Plant stunted, weak growth, leaves off color or limbs dying Powdery mildew (white powdery fungus on leaves), rusts (red, black or orange spots on leaves), leaf spot (black spots on leaves borer damage to stem or leaves, look for holes in stems or leaves Poor soil drainage, drought damage, excess soil drainage, planting too deeply, improper soil pH, cold damage, lawn mower damage, sunscald, stem breakage, animal damage Consider working organic matter into soil before planting shrubs or trees to help improve soil aeration and water-holding capacity. Lack of water is the primary cause of death to recently transplanted shrubs and trees
Plants dying suddenly Root rots (fungus) Insect larva attacking roots Over fertilizing, severe drought damage, poor soil preparation When root rot damage is moderate, symptoms may be similar to those of drought damage
Yellowing (chlorosis) Viruses may cause a mottled appearance on the leaves Insect damage to stem or stippling of leaves Nutritional deficiency (N, Zn or Fe), poorly drained soil, over fertilization, mechanical damage to stem N deficiencies occur on lower leaves first and move up the plant. Fe deficiencies result in interveinal chlorosis of the upper leaves first.
Browning of margin or edges of leaves Root rot (fungus) Frost or cold damage, drought damage, transplanting shock, poor soil drainage, excessive fertilization, mechanical damage Frost damage usually occurs in early spring as buds leaf out. Damage may not be visible for a month or more.
Plant fails to flower Bud blight and other fungal diseases of the flowers Aphids, thrips, grasshoppers, and other chewing or sucking insects Plant is too young or excessive vegetative growth over shading High N levels in soils and ideal growing conditions may delay flowering of some plants.
Plant fails to produce berries Fungal diseases at flowering Cold or frost during flowering, plant is a male or a male plant is missing with only female plants present, improper pruning Using hedge shears to prune shrubs usually results in the removal of most of the tip growth and future flower buds. Berry-producing plants are best pruned by removal of individual limbs inside the plant.
Loss of berries before maturity Fungus disease on berries insect larva Drought damage In mild to moderate attacks by floral diseases, the berries may be discolored or deformed.

Taken from: Perennial Ornamental Plants. H.S. Fenwick, Extension Plant Pathologist. University of Idaho College of Agriculture. Current information Series 146, 1977.


 August 13, 2012
Aug 132012
 
  1. Insects – may include chewing or boring into leaves and stems, or plant parts missing altogether. Leaves may be curled, skeletonized (only the leaf veins remain while the tissue between the veins is missing) or have dead spots from insect feeding. Insects may also spread bacterial, fungal, or viral diseases from plant to plant.
  2. Pathogens (diseases) – includes viruses, bacteria and fungi. Leaves may have circular or irregular patterns of dead or discolored tissue or be completely covered in spores from fungi.
  3. Non-infectious (physiological) – includes nutrient deficiencies and toxicities, environmental stresses, or damage caused by chemicals, animals, weather or equipment
Five Steps to Complete When Diagnosing Plant Problems
  1. Identify the plants species and cultivar if applicable – Determine if growth is normal? Did the plant grow abnormally this year, or did it grow at all? What is the leaf shape and size compared to ideal?
  2. Look for patterns – Are other plants in the area affected too? Are the symptoms uniform or random? Is more than one species affected?
  3. Determine what part(s) of the plant are affected – Are the roots, stem, leaves or branches affected? How has the damage progressed over time?
  4. Look for visible symptoms (abnormal appearances or characteristics of plants) and signs (indirect or direct evidence of a pathogen or insect) – chlorotic (yellowing of plant foliage), necrotic (browning and death of plant foliage), contorted growth, damaged or missing parts. What are the leaf patterns and color? Are any signs of the insect or disease (visible insect body parts or fungus spores) present?
  5. What are the environmental and cultural situations present? Ask questions about management practices (watering and fertilizing), history of the area, weather, soil, and handling of the plant. Find out the current history of the area where the plants are growing. What fertilizers or pesticides have been used? What is the irrigation system and how much/how little water has been applied and when?
 August 13, 2012
Aug 102012
 

Dry climates limit the number of diseases that are common in vegetable gardens but there are a few serious problems that should be monitored.

Viruses

A number of common virus diseases occur on vegetable crops. These include, but are not limited to, zucchini yellows, cucumber mosaic, potato leafroll virus, tomato spotted wilt, and tomato mosaic. The only solutions to a virus infection is removal of the affected plants and control of the vectors (other organisms, usually insects, that spread the disease). Control of a serious recurring virus problem may require getting help from a Master Gardener, county extension educator, nurseryman, or other qualified person.

Corn SmutBacteria

Many of the fruit rots and some leaf spot diseases are caused by bacteria. There are no chemical controls for bacteria. The best methods for controlling these diseases are cultural. Keep fruit off the ground and make sure irrigation practices allow plant surfaces to dry between watering. Also, from the garden any refuse from diseased plants.

Fungi

The most common diseases of plants involve fungal pathogens. Some fungal diseases live in the soil and attack the plant through the roots; other fungal pathogens directly attack leaves, stems, flowers, and fruits. Soil diseases are usually controlled through crop rotation, meaning moving each vegetable to a different place in the garden each year. Fungal leaf and fruit diseases can be reduced my allowing foliage to dry between irrigations and keeping plant parts off the ground. Occasionally, fungal diseases may require fungicidal applications.

To learn more about controlling diseases in vegetable gardens, use the following resources:

University of Idaho: Management of Vegetable Diseases in Home Gardens
Cornell University: Minimizing Diseases in Vegetable Gardens
University of Illinois: Controlling Diseases in the Home Vegetable Garden

 August 10, 2012
Aug 102012
 

The most important tool in managing pests and diseases in your orchard is regular scouting. At least weekly, closely examine the trunks and branches, flowers, leaves, and fruit for signs of pests or diseases. If you are not sure what a problem is or how to control it, get help from your county extension office, nursery or garden center.

Just as the buds are swelling, but before they open in early spring, you may wish to apply a spray of dormant crop oil. Even better is a mix of dormant oil and sulfur. The oil helps control pests by smothering the overwintering pests and eggs. Beneficial insects and mites that feed on these pests usually overwinter elsewhere and are not harmed by the oil. Various sulfur formulations are available to gardeners for dormant applications are very valuable in helping manage fungal diseases. Your garden center can advise you on suitable products. Always follow label directions and regulations carefully. Some dormant oils and sulfur treatments are approved for organic fruit production.

 August 10, 2012
Aug 092012
 

Inspecting a treeAbout this time of year, I begin to experience what I call “garden itch”. I really want to get out and dig in the dirt and make something grow. Garden books tell us winter is the time to study garden catalogues, complete seed orders, and make plans for the next spring. While fun, these activities don’t seem to satisfy my itch.

However, all is not lost. There is one important gardening activity that is best completed in the winter. It involves conducting a thorough tree inspection. This is especially effective for deciduous trees because they no longer have leaves to hide their problems. So, on a sunny winter day, put on your hat and boots and take a close look at your trees.

What to look for:

Although winter may not be the time you want to solve tree problems, it is the time to identify them. Here is a list of things you may want to look for.

Inspecting a treeStructural Problems: look for situations that can be early signs of weakness that may later lead to branch or tree failure. Many of these can be solved later on through judicious pruning. Specifically, look for branches with a poor attachment angle. Where they join the trunk, branches should be directed slightly upward at an angle of 45 to 60 degrees. If they are too horizontal, or too upright, they will become weak. Plan to remove such problem branches, if it can be done without destroying the structure of the tree.

Inspecting a treeAlso, look for cracks and splitting around branch junctions. If you find such damage on large trees, you may need to access some professional help to determine the best action. On small trees, you can reshape the tree to relieve the pressure that is causing the problem and help the tree heal itself. The last thing to look for is something called included bark. This is a situation where the tree does not make normal wood on the top of the branch junction and instead produces bark in the joint. It can be recognized by the soft, corky tissue (it may create an open crevice or be closed) that is present on top and down into the branch union. This makes the branch very weak. It is often associated with a steep branch angle. Plan to remove these weak branches if feasible.

Inspecting a treeArchitecture and Appearance: When the tree is bare, you can step back and look at its overall growth habit. Determine whether or not it has good balance and overall appearance. Decide if the crown needs to be raised, lowered, or cleaned (but never topped). Record a pruning plan that can be implemented in the spring to improve the tree’s appearance and functionality.

Pests and Disease Problems: Although pests are typically not damaging during the winter, it is still a good time to look for problems that can be addressed during spring or summer. Some of the most destructive insect pests on trees are borers. Look for the small holes, the sawdust-like frass, or loosened bark that may indicate a problem is looming. Other types of insects such as aphids or beetles will overwinter as eggs on the trees and may become problematic next summer. Do some homework before the inspection and find out what to look for based on common problems for the tree species you are inspecting. Also, check for disease problems that appear as cankers on the bark. If you find such problems, study up on the solutions and prepare to deal with them when the season is right. That will give you one more scratch for the gardening itch.

A good winter tree inspection will identify problems you may not know you have. It will also give you time to come up with a good solution to one or more of the many issues that affect tree health. Winter may be a slow time for garden chores, but it does not need to be unproductive.

—Stephen Love, Consumer Horticulture Specialist

 August 9, 2012
Aug 092012
 

The term “organic farming” was first used in England in the early 1940s, emerging from the biodynamic movement in which a farm was perceived spiritually as a dynamic, living “whole organism.” The concept was brought to the United States in the mid 1940s and widely promoted by J.I. Rodale, founder of Organic Farming and Gardening Magazine (now Organic Gardening) and author of Pay Dirt: Farming and Gardening with Composts and How to Grow Fruits and Vegetables by the Organic Method. Rodale strongly believed in the relationship between living soil and healthy food was achieved by returning animal manures and plant debris to the system by way of composts. The United States Department of Agriculture defines organic as as “an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony.

The growing and selling of produce and products labeled “Certified Organic” is strictly monitored by the United States Department of Agriculture involving a rigorous certification process and complicity with federally mandated regulations for exclusion of non-approved crop management materials, such as synthetic pesticides and fertilizers.

Many home gardeners would like to reduce synthetic chemical use around their children, pets and environment. While they won’t need to certify their backyards, home gardeners may adopt some of the recommended practices to grow flowers, vegetables, fruits and even lawns by using biological and cultural controls, composts, and organic fertilizers along with conventional methods. Some gardeners may choose to completely exclude the use of inorganic fertilizers or growth regulators to reduce dependence on non-renewable resources. Whatever the desire and intent, there are some universally applicable concepts that will help the organic gardener succeed.

closeup of row of seedlings in dirtOrganic vegetable gardening promotes and enhances natural diversity and biological cycles. Rather than relying on synthetic fertilizers and pesticides, organic gardening is based on making the garden self-sufficient and sustainable. You can ease your gardening practices into the organic arena by starting with some of the easier aspects of organic gardening, such as mechanical control of weeds and insect pests.

The first step in this transitioning a garden to organic is improving and maintaining soil fertility and quality. Healthy, fertile soils are basic to successful organic vegetable and fruit production. Management and addition of organic matter, in the form of composts, manures, green manures, and plant residues, is the most important principle to understand for maintaining soil productiveness in an organic system. Organic matter in various forms should be added to the soil annually. There are also many organic fertilizers that can be used to supplement plant nutrition, especially to meet the need for nitrogen and phosphorus. Utah State University has published an excellent organic fertilizer guide, Selecting and Using Organic Fertilizers.

Pest management is the most challenging aspect of organic gardening. Weeds can be controlled with cultivation, pulling, or smothering using mulches. Insects must be closely monitored and controlled using various mechanical methods, predator insects, baits and traps, mild soaps or directed water streams. There are several organically certified insecticides that are useful in the control of insect pests, including Bacillus thuringenisis, insecticidal soaps, rotenone, or natural pyrethrins.

Diseases are best managed through the use of resistant varieties. It is also important to purchase and plant disease-free seed to avoid introducing disease pests into the garden as well as remove and discard diseased plants, rotate annual crops to different places in the garden each year, and keep the garden area free of weeds and dead plant material that may harbor disease organisms. Some leaf-infecting fungi can be controlled using organic fungicides.

A comprehensive list of approved organic materials can be found on the Organic Materials Review Institute web site.

Organic gardening can be simple or complex, depending on the desires of the gardener. There is plenty of good information available on the topic from numerous authoritative sources. Here are some of the best:

View a simple introduction to organic gardening concepts from Mississippi State University

For information on a straightforward, but more detailed approach to organic vegetable gardening, visit this list of University of Florida publications.

For an in-depth discussion of organic soil management principles, read Producing Garden Vegetables with Organic Soil Amendments from the University of Florida.

If you wish to move beyond a cursory understanding of organic gardening practices, select from a series of publications from the University of California, Davis describing detailed organic production principles.

 August 9, 2012
Aug 062012
 

Gardeners like to improve their soils, and often do so by adding composts, manures, straw, sawdust, or other organic materials. There are both benefits and risks associated with soil amendments. Perhaps the greatest advantages to organic soil amendments are that they can increase water and nutrient holding capacities on light-textured soils and can be sources of plant nutrients.

Amendments also carry risks. Weeds, pests, and diseases can easily be brought into your garden through contaminated organic materials. Woody materials, such as straw, bark, and sawdust, can create severe nitrogen deficiencies in the soil as they decompose. Woody materials are broken down by microorganisms in the soil. These microorganisms take nitrogen from the soil to use for proteins and other compounds in their bodies. Until the woody material is decomposed and the microorganisms die, the nitrogen is unavailable to plants. An excellent strategy to avoid importing weeds, pests, and diseases and to avoid depleting your soil nitrogen is to thoroughly compost organic amendments before adding them to your garden.

Learn more about composting here.

 August 6, 2012
Aug 032012
 

Two distinct types of pears varieties are available: standard and Asian. Asian pears are rounder and crisper than standard pears, and are sometimes likened to apples. Pears are less hardy than apples and can suffer freezing injury in some parts of Idaho. The buds and wood of standard pears are typically hardy to about -25°F. Standard pears are widely grown throughout Idaho, although they can be more difficult to grow in central Idaho and the colder parts of southeastern Idaho. Asian pears are less hardy than standard pears and are best suited to the warmer parts of southwestern Idaho. Pear trees grow to about 18 feet tall, but can be kept nearly any size by training and pruning. For artistic gardeners, pears can easily be trained into espaliers or other exotic shapes and can be trained to grow in a narrow wall along trellises or fences, or flat against walls. You can expect your first crop three to five years after planting. Seedling or Old Home rootstocks are commonly used.

Plant on deep, well drained soil and away from frost pockets. While pears tolerate somewhat heavier soils than most other tree fruits, poor drainage can stunt growth, reduce survival, and reduce fruit crops. Neutral to moderately acidic soils are suitable for pears.

Pears require cross pollination, so plant two cultivars close together. Seckel and Bartlett are not cross fertile and will not serve as cross pollinators for each other. Nearly all pear cultivars are susceptible to fire blight disease, particularly in humid climates. Fire blight can be a problem in Idaho, so try to select varieties resistant to the disease. Pear scab is also a problem disease in Idaho.

 August 3, 2012