| Pine Sawflies | Yellow Poplar Weevil |
| Septoria leaf spot | Spider mites |
| Fall webworm | Bagworms |
| Japanese Beetles | Potato Leafhopper |
| European pine sawfly larvae | Oystershell Scale - crawlers |
| Hawthorn lace bug - egg hatch | Eastern Tent Caterpillar |
| Yellow Poplar Weevil | Adelgids - Alberta spruce |
| Boxwood Psyllids | Brown Patch - Ky bluegrass |
| Brown spot needle blight-Scotch & Austrian Pine |
In 1993, powdery mildew was recorded for the first time in the U.K. Plant Disease Diagnostic Laboratory. Dogwoods showed small, dark red splotches on upper surfaces of otherwise healthy appearing leaves. These splotches developed into brown dead areas on the leaf. Some affected trees also showed a yellow mottling and slight distortion of new leaves as well as yellowing of older leaves, suggesting a nutritional deficiency. These yellowed leaves were also infected with mildew. The white, dusty fungal growths, typical signs of powdery mildew, were not as obvious on dogwood as powdery mildews of most other plants in the landscape. Dogwood powdery mildew has been observed the last couple of seasons with the same symptoms, but, in some cases, they are more severe. Trees are observed to have almost the entire new growth distorted and covered with the mildew fungus. Many leaves have large, brown, dead areas, and again, mildew growth of the causal fungus, Oidium is not obvious. Powdery mildew infections reduce plant photosynthesis and increase leaf water loss partly through the mostly superficial fungal mycelium. Susceptibility of individual dogwood trees in landscapes varies greatly.
Although wet leaves favor most landscape plant diseases, powdery mildew is an exception. Like other powdery mildews, dogwood powdery mildew is favored by humid weather. Germination and infection does not require leaf moisture, and occurs in about 6 hours; new spores are produced in 5 or 6 days.
What is one to do in the face of this continuing menace? First, avoid cultural practices that stimulate succulent growth and encourage powdery mildew. These include applying nitrogen fertilizer, pruning heavily, and irrigating excessively. Continue good cultural practices such as mulching over the root system, pruning out dead branches, providing good air movement, and light penetration by judicious pruning of nearby vegetation. If fungicide applications are being considered for preventing powdery mildew in valuable specimens, be sure that the product chosen has dogwood on the label. Thiophanate-methyl (Clearly’s 3336) has a broad label for control of powdery mildew on many hosts, and propiconazol (Banner), labeled for dogwoods for anthracnose control, should also control dogwood powdery mildew. The fungicides will help prevent infections on healthy leaves, but will not cure leaves already infected.
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The weevils overwinter as adults under ground litter. In late spring, the adults feed on the leaves of musk thistle rosettes and mate. Near the time musk thistles begin to bolt, each female lays approximately 100 eggs on the bracts of developing flowers and covers them with a secretion of chewed plant material. This material gives the eggs a dirty, scale-like appearance.
Eggs hatch in six to eight days. The small grubs tunnel into the receptacle, or swollen base of the thistle flower, where they feed for about 25-30 days. When mature, the larvae enter a resting stage, called the pupa, which lasts another 8 to 14 days. During this time the insect transforms into an adult.
When 15 or more grubs feed within a single head, the thistle plant does not form seeds. Numbers of larvae per head tend to decrease as more flowers develop. Their feeding causes some flowerheads to turn brown prematurely because of damage to the head or to the stem just below the receptacle. Incompletely filled flowerheads with dead plant tissue in the center can be a sign that thistle weevils are present.
One generation of the weevil occurs each year. Adults emerge in July and seek overwintering sites under new musk thistle rosettes, ground litter, and wooded areas where they will remain dormant until the following year.
Note: The UK Department of Entomology has been active in distributing the thistle weevil throughout Kentucky since the mid-1970’s. Distribution this year has centered on 1-64 in Jefferson and Shelby counties and along the Bluegrass Parkway in the Nelson and Washington county areas.
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Adults emerge from the ground and begin feeding on plants in June. Individual beetles live about 30 to 45 days. Activity is concentrated over a four to six week period, beginning in July, after which the beetles gradually die.
Japanese beetles can feed on about 300 species of plants ranging from roses to poison ivy. Odor seems to be a very important factor in the selection of a suitable food plant.
They usually feed in groups, starting at the top of a plant and working downward, and prefer plants exposed to direct sunlight. A single beetle does not eat much; it is group feeding by many beetles that causes the severe damage. Adults feed on the upper surface of foliage, chewing out tissue between the veins. This gives the leaf a characteristic skeletonized appearance. They tend to do little feeding on thick, tough leaves.
The spread of the Japanese beetle is primarily the result of flight of the adults. They can fly as far as 5 miles but 1 to 2 miles is more likely. Usually, they make only short flights as they move about to feed. Local infestations spread as beetles move to favored food and suitable sites for egg laying.
Life Cycle
Egg laying begins soon after adults emerge from the ground and mate. Females leave plants in the afternoon, burrow 2 to 4 inches into the soil in a suitable area, and lay their eggs. Females lay 1 to 4 eggs every 3 to 4 days for several weeks - a total of 40 to 60 during their life. The grub or larval stage hatches from the egg.
The Japanese beetle spends about 10 months of the year in the soil as a white grub. The grubs grow quickly and by late August are almost full-sized (about 1 inch long). Grubs feed on the roots of living plants, doing the best in warm, slightly moist soil that has plenty of organic matter and tender grasses. However, they can survive in almost any soil in which plants can live.
Late summer rainfall is needed to keep eggs and newly hatched grubs from drying out. During dry summers, females lay their eggs in low, poorly drained areas. The grubs are relatively drought resistant and will move deeper into the soil if conditions become very dry. Japanese beetle grubs also can withstand high soil moisture, so excessive rainfall or heavy watering of lawns does not bother them. Grubs usually move less than 30 inches in sod or turf; however, measurements have shown that grubs can move as much as 16 feet in fallow soil. generally, they will not move far unless food becomes scarce or soil conditions become unfavorable.
As white grubs chew off grass roots, they reduce the ability of grass to take up enough water to withstand the stresses of hot, dry weather. As a result, large dead patches, 5 to 20 feet in diameter, develop in the grub-invested areas. The sod on these dead patches is not well-anchored and can be rolled back like a carpet to expose the grubs. If the damage is allowed to develop to this state, it may be too late to save the turf. Early recognition of the problem can prevent this destruction.
Japanese beetles overwinter in the grub state and survival is good under Kentucky conditions. When the soil cools to about 60°F in the fall, the grubs begin to move deeper. Most pass the winter 2 to 6 inches below the surface though some may go as deep as 8 to 10 inches. They become inactive when soil temperature falls to about 50°F.
When soil temperature climbs above 50°F in the spring, the grubs begin to move up again. Following a short feeding period, the grubs pupate in an earthen cell and remain there prior to emerging as adults.
Control
The insecticides listed below may be used to control Japanese beetles along with those listed in other publications. Repeated applications may be necessary because of the relatively short residual effect of the products. Also, significant rainfall shortly after an application may reduce the insecticide deposit below effective levels.
Plants which grow rapidly and are especially attractive to the beetles are most difficult to protect. Roses unfold quickly and are especially attractive to beetles. When beetles are abundant, nip buds and spray to protect the leaves or cover the roses with netting to keep beetles out.
Be sure the insecticide you use is registered for use on the crop you spray. Products labeled for control: Malathion, Orthene, Scimitar, Sevin, Talstar, Tame, Tempo, Turcam
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Their results discovered marked differences in susceptibility among cultivars. The following list was based on three years of evaluations for crabapples and two years for lindens and roses.
Flowering Crabapples Cultivars (Large Trees)
Extremely Susceptible (80-100% defoliation) Radiant, Red Splendor, Royality, Liset, Ruby Luster, Hopa, Dolgo
Highly Susceptible (50-80% defoliation) Candied Apple, Beverly, Selturk, Henningii, Velvet Pillar, Robinson
Susceptible (30-50% defoliation) Adams, Indian Magic, Red Barron, Ralph Shay, Bob White, Mary Potter, Sentinel, Sugar Tyme, White Cascade, Molten Lava, Donald Wyman, Professor Sprenger, Ormiston Roy, Snowdrift, Tshonskii, Profusion
Relatively Resistant (15-20% defoliation) Christmas Holly, Silver Moon, Floribunda, Strawberry Parfait, Zumi calocarpa, Red Jewel, Halliana parkmanii
Resistant (15-20% defoliation) Red Jade, David
Highly Resistant (<15% defoliation) Jewelberry, Harvest Gold, Baccata v. jackii
Flowering Crabapple Cultivars (small trees)
Extremely susceptible (75-100% defoliation) Radiant, Beverly, Dolgo, Purple Prince, Red Splendor, Tina
Highly Susceptible (50-75% defoliation) Indian Summer, Pink Princess, Candymint Sargent, Snow Magic, Velvet Pillar, Coralburst
Susceptible (25-50% defoliation) Brandywine, Doubloons, Zumi ‘Winter Gem’, Sinai Fire, Edna Mullins, Adirondack, Naragansett, Centurion
Relatively Resistant (15-25% defoliation) David, Floribunda
Highly Resistant (<15% defoliation) Bacatta v. Jackii, Louisa, Harvest Gold, Jewelberry
Linden Species and Cultivars
Extremely Susceptible (80-100% defoliation) Tilia cordata “Greenspire’, T. cordata ‘Olympic’, T. cordata ‘Chancellor’, T. cordata ‘Glenleven’, T. americana ‘Redmond’, Tilia x euchlora (Crimean)
Susceptible (50-75% defoliation) Tilia tomentosa ‘Sterling’
Somewhat Less Susceptible (20-50% defoliation) Tilia americana ‘Wandell Legend’
Hybrid Tea Rose Cultivars
Highly Susceptible (>75% defoliation) Voodoo, Princesse de Monaco, Gardens of the World, Cary Grant, Confidence, Perfume Beauty, American Spirit, Milestone, Perfume Delight, Carden Party, Antiqua, Friendship, Unforgettable, Perfect Moment, Olympiad
Susceptible (60-75% defoliation) Touch of Class, Allspice, Dolly Parton, Lanvin, Sunbright, Tropicana, Tiffany, John F. Kennedy, Brigadoon, Gina Lollobrigida, Christian Dior, Headliner, Oregold, Browdway
Somewhat Less Susceptible (40-60% defoliation) Dynasty, Graceland, Ambassador, King’s Ransom
Floribunda Rose Cultivars
Highly Susceptible (70% defoliation) Sunflare, Marina, Class Act, First Kiss, Angel Face
Susceptible (>60% defoliation) All That Jazz, Gingersnap, Cherish, Amber Queen
Grandiflora Rose Cultivars
Highly Susceptible (>70% defoliation) Sonia, Fragrant Memory, White Lightnin’, Love, Arizona, Shining Hour
Susceptible (60-70% defoliation) Lagerfield, Jardins de bagatelle, Spellcaster, Tournament of Roses
Relatively Less Susceptible (40-50% defoliation)
New Year
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Interestingly, azoxystrobin was derived from, and is chemically very similar to, a class of naturally occurring fungicides called strobilurins. These are chemicals produced by various wood decay fungi. These fungi produce these to eliminate other fungi from competing with them for nutrients.
As with all systemics, there is some concern about the possibility of resistance to Heritage. Users should use the product wisely, and avoid overuse of the product. Read the label carefully for some of the guidelines relating to resistance management.
I have conducted research with Heritage for two years, and have seen quite a bit of data from other field trials with the product, as well. Below is a summary of approximate efficacy of the product for several diseases of interest to turf managers in Kentucky.
Brown patch and anthracnose. At labeled rates, this is an outstanding product, the best available for both diseases. This product will definitely make easier the job of controlling these summertime diseases.
Dollar spot. Heritage is not labeled for dollar spot, nor does it have any activity at normal use rates. In some tests, including one of my own, the product actually enhances dollar spot activity. The fact that dollar spot can sometimes continue to increase in Heritage-treated plots while declining in others suggests: (1) something besides, or in addition to, hot weather causes dollar spot to decline in mid-summer; and (2) that turf managers working with grasses susceptible to dollar spot should be especially aware to practice sound fungicide resistance management practices where Heritage is used regularly. Resistance in the dollar spot fungus to benzimidazoles occurs regularly in Kentucky, and resistance to the ergosterol inhibitor fungicides (also called DMI fungicides) also has occurred several times.
Pythium blight. Heritage is labeled for Pythium blight, but this is not its greatest strength. It is labeled for use at a high rate of 0.4 oz ($8.75/1000 sq ft), and then provides protection for no more than 10-14 days under high disease pressure. Heritage shouldn't be the only Pythium fungicide used, and the labeled restricts the uses from more than two back-to-back applications against Pythium blight.
Summer Patch. I've seen only a few studies on the efficacy of Heritage against summer patch, but what I've seen looks excellent.
Pythium Root Rot. Data on the efficacy of Heritage against this poorly understood disease complex are extremely limited. It is labeled and may perform well, but there is insufficient experimentation for recommendations to be made.
Pink Snow Mold. While labeled, the product is somewhat weak against pink snow mold (also called Fusarium patch and Microdochium patch). It must be tank-mixed for best results, but there are other products that are quite effective by themselves against this disease.
Take All Patch. I've seen results of few studies against this disease, but it appears to be very good, especially if both spring and fall applications are made. It is nice to have other options against this disease, which appears to be increasing in importance nationwide.
