Inspector Findings in Kentucky

Transcription

1 Inspector Findings in Kentucky Volume XVII, Issue III Office of the State Entomologist August Inside this issue: Daylily Leafminer 2 Fall Webworm 2 Decline of White Pine 3 What to Look For 7 Thousand Cankers Disease Confirmed in Ohio 8-9 Cover photos Fall webworm tent, and annual cicada By Katie Joya

2 Page 2 Daylily leafminer Lee Townsend, Extension Entomologist Fall Webworm Lee Townsend, Extension Entomologist The daylily leafminer is a relatively new pest (2006) that has been detected in several southeastern states. The small yellow maggots feed in the leaves of Hemerocallisspecies and their cultivars, leaving obvious silver tunnels. The leafminer does not appear to kill plants but there is a obvious cosmetic impact. There are several generations each year and activity can persist until leaves senesce. The adult, which resembles a very small house fly, can be seen resting on daylily blooms. No specific chemical controls have been developed but contact insecticides applied to the foliage generally will not penetrate the plant to kill the larva. Removing and destroying infested leaves may reduce populations somewhat. Figure 1. Daylily leafminer tunnel in Fayette County. Reddish object at the end of the tunnel is a pupa. Fall webworm caterpillars build light gray silk tents that contain the ends of branches of trees and shrubs. These large conspicuous webs contain caterpillars, covered with long white to yellow-tan hairs and two rows of black marks along their bodies, dead or partially eaten leaves, and lots of small black droppings. The insect can feed on over 90 species of deciduous trees; hickory, walnut, birch, black cherry, and crabapple and mulberry are favorites. Fall webworm larvae incorporate the leaves they are eating into their tent which is enlarged to include more foliage as the caterpillars grow. They feed for about 4 weeks and are just over an inch long when full-grown. They can be numerous enough to completely defoliate small trees and shrubs but this is not common. Usually, little real damage is done to trees but the ugly webs and brown are unsightly. Accessible nests can be pruned out and discarded, if practical. Insecticides containing Bt, spinosad, Sevin, or pyrethroids can be used if chemical control is necessary and the sprayer can reach foliage around the nest. There are two generations in Kentucky each yearfrom mid-june to early July and again in August.

3 Page 3 Decline of White Pine Nicole Ward Gauthier, Extension Plant Pathologist Decline is common among white pine in Kentucky. Two distinct diseases with similar names are often confused, but they are distinctly different. Note that white pine decline is an abiotic malady that leads to slow decline, while white pine root decline is a fungal disease that causes sudden plant death. More details follow: White Pine Decline Symptoms White pine decline causes needles to yellow and drop prematurely, causing a noticeable thinning of the canopy (Figure 2). Other symptoms include unusually shorter needles; needle tips may become brown. Bark of individual branches may become shriveled and needles on those branches become wilted or limp (Figure 3). Disease Management The best way to manage white pine decline is through prevention. Select sites with the following characteristics: - Acidic soil (ph of 5.5 and not above 6.5) - Sandy or loamy rather than clay soils - Large area for root development - Loose soil free from soil compaction - Sufficient soil moisture (regular irrigation and mulch) - Vigorous plants (control insect pests and fertilize trees regularly) Once decline begins, it may be difficult to reverse. However, the following practices may be implemented: - Lower soil ph by applying granular sulfur according to soil test results - Aerate soil by vertical mulching or other means - Fertilize and water to eliminate stress Trees may be infected for several years without showing symptoms. However, once symptom development begins, homeowners often notice delayed bud break and reduced candle elongation in spring. Mature foliage then fades, droops, and turns brown rapidly Conversely, nearby trees may appear healthy; mortality appears quite random with a few trees dying each year. Resin flow (pitch) is visible at the tree base and is associated with a dark brown girdling canker under the bark. The trunk may be flattened on the affected side. Cause White pine decline is not caused by a pathogen. Symptoms are induced by environmental conditions such as: - High soil ph - High soil clay content - Restricted root-growth - Compacted soil - Mechanical disturbances that cause root injury

4 Page 4 White pine root decline is caused by the fungus, Leptographium procerum that infects inner bark and sapwood of roots and lower trunks of white pine. Although the disease is most serious on white pine, the fungus also can infect Scots and - Collect samples for diagnosis by removing tissue from the canker face (bark removed) and shipping in a plastic bag. Austrian pines. Losses within an infected planting may range from 20% to 50%. Trees planted on wet sites are more susceptible to infection, although other stresses may also cause trees to become susceptible to the disease. Once infection occurs, the fungus may be spread from tree to tree by contaminated insects as they move from diseased trees to healthy trees nearby. Galleries of insects such as the pine root collar weevil may be found in cankers and provide a place for the fungus to sporulate. Weevils and other bark-infesting insects may serve as vectors for this disease. Disease Management Cultural practices help reduce disease spread by insect vectors. No fungicide is available for disease management. Figure 2. White pine decline, an abiotic malady, is caused by environmental conditions. Symptoms include thinning needles and reduced plant vigor. - Avoid wet sites - Do not replant eastern white pine among stumps of recently killed trees - Remove and destroy infected trees including stumps,

5 Page 5 Figure 3. Wrinkled bark is common on trees suffering from white pine decline. Needles above damaged bark become wilted and drop. Figure 4. White pine root decline, a fungal disease, causes rapid wilting of white pine.

6 Page 6 Figure 5. Rapid wilting is often followed by rapid browning (needles intact) when trees are suffering from white pine root decline. Figure 6. Pitch is often associated with trunk cankers caused by white pine root decline

7 Page 7 What to look for August September European hornet Twigs of lilac, birch, rhododendron July through early Sept Fall webworm Tents at end of branches in various trees Second generation in August Japanese beetle Foliage of host July through August Orangestriped oakworm Red and white oaks July through September Pine needle scale Needles of pines, especially mid- to late July Mugho and Scots, spruce and other conifers Rose slugs Rose leaves mid-july through mid-august Spiny oakworm Red and white oaks July through September Two spotted spider mite Underside of leaves, many mid-july through mid-august plants Woolly alder aphid Alder June through September Locust leaf miner Locust August Mimosa webworm Mimosa August Oak skeletonizer Oaks August Pine webworm Tuliptree scale Va pine, short and longleaf pines Tuliptree twigs and branches August Crawlers in late August Cottony maple scale Magnolia scale Spruce spider mite Twigs of maple honeylocust others Magnolia twigs and branches Needles and twigs of conifers Crawlers in early September Crawlers in early September September

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9 Page 9 Find KY OSE on facebook John Obrycki, Ph.D: State Entomologist Joe Collins: Emerald Ash Borer Coordinator, pest surveys & nursery licenses joe.collins@uky.edu Carl Harper: Slow-the-Spread gypsy moth trapping coordinator, web design & phytosanitary certificates carl.harper@uky.edu JD Loan: survey supervisor, jdloan.1@juno.com Janet Lensing, PhD: State Survey Coordinator, pest surveys janet.lensing@uky.edu Jennie Condra: nursery inspections, pest surveys, outreach coordinator jennie.m.condra@gmail.com Katie Joya: pest surveys, nursery inspections, newsletter katie.kittrell@uky.edu Phone: (859) Fax: (859)