Posts tagged holes

Slimy slugs

Laura Jesse, of Iowa State University Extension’s Plant & Insect Diagnostic Clinic, wrote the following about garden slugs:

 

Slug photo by Laura Jesse of ISU Extension

Slug photo by Laura Jesse of ISU Extension

    There seem to be plenty of slugs in my garden, but I hope not in yours. Slugs leave small, irregular holes all over the leaves of plants. They especially seem to like my hostas but they are not picky feeders. Slugs are difficult to detect because they feed only at night. Slugs look like snails without a shell. They vary in size from less than an inch up to 2 inches in length, grayish colored, and a bit slimy to the touch. In fact as they crawl along they leave a slime trail.

    Slugs need moisture to survive and are found under mulch, rocks, logs, and other damp locations. My hostas tend to be eaten because they grow in a garden that is shaded and holds the moisture longer.

    Reducing slug damage is not an easy task and nothing will fix holes already there, so your first question should be – how bad is this and can I live with the damage? If you do decide to try to reduce the slug population you should combine several tactics. First, remove mulch and reduce moisture from around the base of afflicted plants as much as possible. Remove slugs you find either by using a trap such as a board on the ground that slugs will gather under or pan traps with beer as a bait. I assume cheap beer works fine and would not waste expensive beer on this. Remove dead slugs daily or it will get pretty disgusting. Finally there are commercially available slug baits available containing a molluscicide, but they are best used in the spring or fall.

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Ash trees, anthracnose and Emerald Ash Borer

Linn County Master Gardener, Claire Smith, shares the following about anthracnose and Emerald Ash Borer:

    Anthracnose – big word, hard to wrap your tongue around.  Anthracnose is a common foliage disease of shade trees in Iowa, including the ash tree.  Multiple inquiries to the Master Garden Hort-Line this morning were from folks whose ash trees were dropping leaves, an unusual occurrence in the spring.  A good guess would indicate that most of those folks were concerned that their wonderful ash tree had become infested with the Emerald Ash Borer.   Be aware that experts are seeing if the Emerald Ash Borer has invaded Iowa by crossing the river into the Northeastern portion of the state.

    A bit about each of these diseases: 

    Ash trees can be infested with anthracnose that is caused by a fungus.  There are a number of closely related fungi, but each is host specific to the tree it infects.  Often symptoms appear serious, but generally the damage caused is minimal and doesn’t seriously affect mature shade trees.  Symptoms include tan to black blotches; immature leaves becoming distorted from abnormal leaf expansion; young leaves dying and falling soon after a heavy infection.  If a severe infection does occur early in the growing season, the trees may defoliate and then a new set of leaves may emerge.  Following are some suggestions to decrease the severity of anthracnose and minimize its impact on your tree’s health:

–          Clean up and destroy fallen leaves:  use your lawn mower bagger

–          Prune the tree to remove diseased branches and properly dispose of them.

–          Prune to open the canopy for better air circulation. Fungi relish damp conditions. Pruning is generally not recommended now, but better to prune than lose the tree.

     The Emerald Ash Borer prefers Green Ash and Black Ash Trees, but will tackle any ash when the previous two mentioned have all been killed.  The borers emerge from early spring to late summer, but evidence may not be visible for up to a year.  Signs of infestation are D-shaped holes in the bark of the trunk and branches and shoots growing from the base of the tree which is the most telltale sign.  The beetle will effectively girdle the tree.  

Following are some suggestions to help reduce infestation and impact of the Emerald Ash Borer:     

–          Avoid planting ash trees

–          Learn the signs and symptoms of the Emerald Ash Borer

–          If camping, purchase firewood at or near the campsite but thoroughly inspect firewood prior to purchase

–          Do not bring extra firewood home with you.

     Maintaining a healthy environment for your trees and plants is of utmost importance.  A routine inspection of your yard and garden is necessary.  Discuss abnormalities with your local extension service, Master Gardeners, or a reputable garden center.  Pictures or actual plant samples are wonderful aids in diagnosing problems. 

REMEMBER THE LINN COUNTY MASTER GARDENER PLANT SALE THIS SATURDAY, MAY 16TH FROM 8:00 TO NOON IN THE EXTENSION OFFICE PARKING LOT AT 3279 7TH AVE. IN MARION.

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In search of grubs, and how to treat crabgrass and arborvitae

Linn County Master Gardener, Claire Smith, wrote the following about three of the most frequently asked questions to the Linn County Master Gardener Horticulture Hotline. The HortLine is available to answer questions from 9 am.. to noon and 1-4 p.m. Monday through Thursday  and  9 a.m. to noon on Fridays at (319)447-0647.

 

    One of the commonly asked questions in the spring concerns when to apply pre-emergent crabgrass killer.  Master Gardener Susan Long has this response:  Typically, the blooming of the forsythia or the redbud is a good indicator of when to apply pre-emergent crabgrass herbicide.  Pre-emergents must be applied before the crabgrass germinates. Ground temperatures must be a minimum of 50 degrees. If the material is applied too early, crabgrass seeds that germinate late in the season will not be controlled.  If applied too late, some crabgrass will have already germinated.  In central Iowa, this is usually mid-April to May 1.  However, if the weather warms up early or stays cool longer, then adjustments must be made based on the conditions.  Having a thick, healthy lawn that is fertilized, watered and mowed certainly discourages the growth of crabgrass. 

    Susan also answered a question about arborvitae having brown leaves due to winter burn and whether it will recover and/or should be pruned:  Avoid pruning browned, burned areas from evergreen trees and shrubs in the early spring since these branches may still have viable buds that will produce new foliage when growth resumes.  The brown will eventually fall off.  If the buds did not survive, then prune dead branches back to living tissue.  The affected trees and shrubs should look much better by late June or July.  There is no need to fertilize affected evergreens.  However, if the weather this spring is dry, periodically water evergreens to encourage new growth and speed their recovery.

    Another caller wondered what causes a lawn to be torn up at night.  Lawns that have grubs attract raccoons, skunks, and crows which turn over large patches of turf in search of the grubs.  The best time to treat is early in the summer when insecticides have the best changes of working.  The entire lawn may not need to be treated, rather treat grub “hot spots” determined by observation or sampling.  Presently trichlorfor (Dylox or Bayer 24-Hour Grub Control) and Sevin are the fastest-acting, most effective homeowner insecticides for curative grub control.  These must be watered in completely after application.  In many cases it may be preferable to repair the damage through seeding or sodding without treating.  If the old, loose sod is still green it may reattach with adequate watering.

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