HL Issue 26 2007

What's Hot HL 26

Brown marmorated stink bug adults and nymph.

Photo by Gary Bernon, USDA APHIS, Bugwood.org

Western conifer seed bug.

Photo by Whitney Cranshaw, Colorado State University, Bugwood.org

Southern red mite.

Photo by John A. Weidhass, Virginia Polytechnic Institute and State University, Bugwood.org

Spruce spider mite with webbing.

Photo from USDA Forest Service - Region 4 Archive, USDA Forest Service, Bugwood.org

Weed Hotline Issue 26

Mesotrione effect on crabgrass and nutsedge.

Mesotrione effect on plantain and Oxalis.

Control of crabgrass with mesotrione in turf.

All photos from the presentation "Mesotrione for Weed Control in Warm- and Cool-Season Turf" by Travis W. Gannon, Fred H Yelverton, and Leon S. Warren, North Carolina State University, Department of Crop Science. To view the full presentation go to http://www.turffiles.ncsu.edu/extension/presentations/2006/Mesotrione_WeedControl.pdf

Insect Hotline Issue 26

Elongate Hemlock Scale Adult Flipped

Elongate Hemlock Scale Crawler

Elongate Hemlock Scale Nymph

Unhealthy Hemlock Attacked By Elongate Hemlock Scale

All Photos by Casey Sclar, Ph. D., Plant Health Care Division Leader, Longwood Gardens

-------Special Alert--------

Chrysanthemum White Rust

Chrysanthemum white rust found in Delaware on Oct. 4, 2007

Chrysanthemum white rust caused by the fungus Puccinia horiana affects cultivated chrysanthemum plants in the Family Asteraceae. The disease is not established in U.S. chrysanthemum production, and could have significant impact on both greenhouse and outdoor plants of chrysanthemum, as well as cut flowers. The disease has occasionally been found in United States nursery stock in greenhouses, but it is easily and quickly cleaned up when found. Symptoms include yellow spots on the upper surface of the leaves that are up to 5 mm in size. On the underside of the leaves, raised bumps or pustules develop which have a waxy, warty appearance and are light in color. If you see signs of white rust on leaves or flowers of a plant purchased recently in Delaware, please take it to your nearest County Extension Office or contact the Delaware Department of Agriculture. Plants should be destroyed.

From Nancy Gregory, Plant Diagnostician, Department of Plant & Soil Sciences, University of Delaware

HL Issue 25 2007

HL Issue 24 2007

What's Hot HL 25

Peach tree borer can damage ornamental cherries and plums.

Photo from Peach Orchard News, Alabama Cooperative Extension

Boxelder Bug

Photo from Whitney Cranshaw, Colorado State University, Bugwood.org

Weed Hotline Issue 25

Calcitic granular limestone. This will be the most commonly used liming material.

Dolomitic granular limestone. Use dolomitic lime sources only if magnesium is called for from soil tests.

Drop spreaders apply lime evenly and overlap problems are less likely.

Liming trial on beach plums. Lime incorporation is recommended when possible.

Liming of acid loving plants can cause micronutrient deficiencies.

Insect Hotline Issue 25

SPRUCE SPIDER MITES. Spruce spider mites are “cool season”

mites commonly found feeding on fir, arborvitae, spruce,

Douglas-fir, and other conifers. Their sucking mouthparts cause

bleaching, yellowing, stippling or bronzing of the needles.

Spruce Spider Mite Pictures from USDA Forest Service - Region 4 Archive, USDA Forest Service, Bugwood.org

Disease Hotline Issue 25

As a follow up to the information in Hotline provided by Bob Mulrooney, the following is additional information from the Plant Clinic of the Morris Arboretum of the University of Pennsylvania.

Drought

Too little water can cause wilting, leaf scorch (browned leaf edges), early fruit drop, stem dieback and plant death. It can also make a plant more susceptible to harmful diseases and pests. Plants draw in water from the soil, use it for plant growth, and then water is released from stems and leaves through a process called transpiration. Plants begin to wilt and suffer drought stress when the transpiration rate exceeds water up-take. Drought is most prevalent in the long days of the summer and can also effect evergreens during dry, windy winters. Also, dry breezes contribute significantly to drought stress.

Signs of drought stress

During a drought, especially such a prolonged drought as we are having, plants may exhibit any of the following:

>upward curling or rolling of leaves

>yellowing and browning of leaves, particularly along leaf edges and tips

>interior needle and leaf drop on conifers

>leaf, blossom, and fruit drop

>under-sized leaves

>twig and branch dieback

Tips for helping your trees during the drought

1) Keep moisture in by laying a 2 inch layer of mulch from the base of the tree out to its drip line to reduce evaporation from the root zone. Remember to keep mulch over the ground under the tree, but not touching the tree's trunk. Also, make sure the soil around your plant is wet before putting mulch on top of it. You want to hold the moisture in with the mulch, but if there's no water in the soil to begin with you will not achieve anything.

2) Keep the area around the tree's root zone free of weeds to avoid competition for water.

3) Focus on the hardiest plants that have the best chance of survival during this drought. Plants recently planted (within the last 2-3 years) will suffer the most as they are still getting established to the new environment.

4) It is often said that pruning will reduce a plants water intake; however, for this to be a significant reduction, at least half of a tree's foliage would have to be removed. During these hot, sunny days, a plant needs all of its foliage to protect it from sunburn. Because pruning is essentially wounding a plant, a severe pruning job could kill a plant at anytime of season or in any weather. Most horticulturists and arborists are recommending that trees and shrubs should not be pruned during this severe drought. Only prune now if a hazard situation needs to be corrected.

Long-term consequences of Drought

>increased susceptibility to attack by insect borers

>increased susceptibility to certain plant diseases

>root death

>decreased winter hardiness

>dieback and death to branches and twigs in the upper canopy

>eventual plant death

Watering

When: water when your soil is so dry that it cannot be formed into a ball, when you see your plants beginning to wilt, or when the needles of conifers turn a dull green to yellow color.

What time: Water in the early morning or evening. Also, be aware of your towns restrictions on the hours in which you are permitted to water.

How much: The amount of water and frequency of which you have to irrigate will depend on the plant. A good rule to follow is to apply 1 gallon of water per square foot of root zone once a week. Vegetable plants with fruit will usually need to be watered more than once a week.

Watch your plants - they will tell you when they need water by wilting. Also, examine your soil - sandy soils will need to be re-watered more often than soils with high levels of clay.

Application: Water plants slowly and watch to see that the water is soaking into the soil not just running off. You want to make sure that the water is reaching the root zone of your plant.

Using soapy water (gray water): water from washing your clothes or dishes can be used around outdoor plants. The recycled water you want to avoid giving to your plants is any water containing chlorine bleaches. Also, avoid splashing the water on the leaves of your plants. The combination of sun, soap and water could cause the leaves to get burned.

View this information at http://www.upenn.edu/paflora/plantclinic/drought.htm

Weed Hotline Issue 24

Bamboo Herbicide Control Evaluation Site

Red-margined bamboo cover 58 wk after treatments were applied (A, nontreated control; B, imazapyr 1.7 kg ai/ha; C, glyphosate 4.5 kg ai/ha).

Trenching to Sever Rhizomes

Table 3 and above three photos from Weed Technology, Article: Volume 21, Issue 1, Jan. 2007, pp. 80–83. Controlling Bamboo (Phyllostachys Spp.) with Herbicides, Mark A. Czarnota and Jeffrey Derr

Insect Hotline Issue 24

Various Forms of the Multicolored Asian Lady Beetle

Photo by Pennsylvania Department of Conservation and Natural Resources, Bugwood.org

Multicolored Asian Lady Beetle

Photo by Bill Ree, Texas A&M University, Bugwood.org

Disease Hotline Issue 24

Cercospora on Sourwood

Photo by Bob Mulrooney, University of Delaware

Walnut Anthracnose

Photo from the University of Minnesota Yard and Garden Line News

Tar Spot on Maple

Photo by Steven Katovich, USDA Forest Service, Bugwood.org

What's Hot HL 23

Aschocyta Blight on Lily-of-the-Valley

Photo by Bob Mulrooney, University of Delaware, Extension Plant Pathologist

Anthracnose on Walnut

Photo From an Online Guide to Plant Disease Control, Oregon State University Extension

Scoliid wasps are usually considered beneficial insects because they help control green June beetle and other grubs.

Photo from the University of Minnesota

Scoliid Wasps Searching and Feeding

Photos by Brian Kunkel, Extension Ornamental IPM Specialist, University of Delaware

Weed Hotline Issue 23

Japanese Stiltgrass Close Up

Japanese Stiltgrass Competing with Planted Ferns

Stand of Japanese Stiltgrass in Wooded Clearing

Japanese Stiltgrass Mowed Area Showing Regrowth

Japanese Stiltgrass Mowing Effects

All Pictures by Susan Barton, University of Delaware, Extension Ornamentals Specialist