Inspector Findings in Kentucky

Last issued we gave you information concerning the finding of Asian longhorned beetles in Crepe Myrtle bonsai plants that came from China. After close examination, it was determined that the insects were not Asian longhorned beetles but rather citrus longhorned beetles. This is still a pest that is not native to the United States. It is our understanding that APHIS has contacted the businesses and individuals who received these plants and has ordered that they be returned to Atlanta. The plants will most likely be destroyed to limit the possibility of the pest becoming established.

Nursery inspectors in Kansas and Missouri have been finding weevil larvae and pupae in B&B spruce trees (4-5ft) shipped from Wilson Nursery, Oregon. The weevil is a relative of the black vine weevil that is native to Europe. It was recently introduced into Canada, and made its way into the US just a few years ago (possibly 1993).

The Missouri inspectors are finding as many as 30 to 50 larvae and early pupae in every root ball so infestations are pretty high. All of the trees found infested are being quarantines ("Stop Sale") for destruction. Reports have it that Wilson Nursery may not be the grower, but they are the supplier for some midwest nurseries in Kansas and Missouri.

If you have any gotten any plants from Wilson Nursery in Oregon, please call us so that we may come and inspect the plants. It would be better to sacrifice a few plants than have to deal with this serious pest.

In mid-May, we got a call from a grower who said that he had October Glory maples that were infested with a borer of some sort. We went out and looked at his trees and determined that the borers were Ambrosia beetles (or pinhole borers). The trunks of these trees were riddled with numerous small holes, some with long tubes of frass sticking out. The tunnels from these beetles were extensive and penetrated deep into the heartwood of trees. The larvae and adults of this beetle bore into hardwoods and softwoods and feed upon a minute fungus (ambrosia) that grows on the walls of the tunnels. This fungus produces characteristic black stains in the wood. These beetles seldom attack healthy trees but will enter a tree through an injured or dying area of bark. The trees at this nursery had been under stress from flooding. Fermenting sap from an unhealthy tree is probably essential for development of the ambrosial fungus that serves as their food. Although these beetles may not actually kill a tree, they undoubtedly hasten the death of sickly trees.

We have pulled from sale and destroyed 27 plants that were being sold at by a major retailer in Kentucky. The plants, called Bur-reed, Sparganium erectum, are aquatic and were being sold as plants for fish ponds. This plant was placed on the noxious weed list because it has the ability to reproduce rapidly and could potentially clog waterways with vegetation.

These plants originated in Holland and were sent to the U.S. along with other five other flower bulbs that are not prohibited in the U.S. Apparently officials did not realize that the plant was a regulated item in the United States.

Once inside the U.S., these plants were distributed within eleven states. The affected states are being notified and the plants are being pulled from sale in each state; hopefully, before they are sold.

This article appeared in the May 1999 issue of Greenhouse Grower page 130.

The latest generation of reduced-risk pesticides comes from a very unexpected source: cinnamon. Cinnamite is made from cinnamon oil. But don't let that fool you, says Brook Murphy, University of California, Davis (UC Davis), an entomologist who has worked on Cinnamite for more than 3 years. "Cinnamite is a compound that is equally effective in controlling all stages of mites and aphids - including their eggs," Murphy says. It also controls a number of important plant pathogens. Murphy says he believes this new biopesticide is truly different from many products on the market. "Cinnamite is a fast-acting and broad-spectrum pesticide," he says. "Plus, it's short-lived in the environment and food-grade safe."

From Spice Rack to Spray Tank

As you might expect, getting the compound from the spice rack to the spray tank was no small undertaking. That's where the product's supplier, Mycotech Corp., entered the picture.

"Cinnamon has a certain amount of insecticidal properties, but it's rather hard on plants," Murphy says. "It's really the formulation that allows us to kill the insects and still use it safely on a wide variety of crops."

Murphy says while the exact mechanism isn't fully understood, he's convinced the product's mode of action is unique and very powerful. This activity helps the product provide rapid knockdown.

"We see results appearing within hours after its application, and the majority of the insects dying within the first day," Murphy says. "This is one of Cinnamite's key advantages. With other insecticides, pests can continue feeding and sometimes even continue laying eggs right up until the point they die 3-7 days later."

It's this quality that makes the pesticide ideal to use when growers are faced with a major pest outbreak just before they ship plants, Murphy says. In addition, Cinnamite can be sprayed right up until the day of harvest without any threat to workers, and it fits most rotational programs.

More Than Just Dead Bugs

Field trials have shown the product's rapid control is not limited to insect pests. Cinnamite has shown fungicidal activity, too. Unlike most of the new reduced-risk pesticides that are extremely focused, this material can control broad categories of pests, from insects to fungi.

Eric Buonpane, a grower with Kitayama Brothers in Watsonville, CA, says he noticed Cinnamite's dual action when he tested the product on some of the operation's 1.4 million square feet of roses.

"Our biggest problems are two-spotted spider mites and powdery mildew," he says. "When we sprayed Cinnamite and got good contact with the mites, it knocked them right down. But what was really interesting was the same application controlled the mildew, too."

The possibility of controlling two different and equally troublesome pests with one compound excites Buonpane. "If we can spray one product that will knock out notes within 24 hours and give us good control of powdery mildew for 4-6 weeks, I couldn't ask for much better than that," he says.

Cinnamite's low toxicity also offers some practical advantages over what Buonpane was using. "Its 4-hour re-entry interval makes a big difference, especially for a rose grower," he says. "With other pesticide products, we have to stay out of the greenhouse all day. But with Cinnamite, we can do a first cut and spray early in the morning and then get back in the greenhouse in the afternoon to do another cut."

Of all the unique benefits the product offers, there's one Buonpane says is hard to miss. "The smell of some of these greenhouse pesticides is just terrible - you feel like you're right in the middle of a chemical factory," he says. "But the cinnamon smell of Cinnamite is really appealing. It makes the greenhouse smell like Christmas all year long.

Safety Counts

Bill Smith, who works in the environmental services department at Briggs Nursery in Olympia, WA, had been experimenting with Cinnamite throughout the operation's 64,000 square feet of woody ornamentals for more than 2 years. And with its recent EPA registration, he's ready to add the compound to the company's pest-control program on a regular basis.

"Some of the other products we've used would be fine one time, and then we'd have a lot of phytotoxicity with our plants the next," Smith says. "But we've found Cinnamite is a lot more predictable. We can use it on more crops under more conditions without having to worry about it burning the plants."

With its unique combination of speed, broad-spectrum control, and safety, UC Davis' Murphy says he expects the new compound to become a mainstay in many growers' integrated pest management programs.

By John Hartman, Extension Plant Pathologist

Many of our most common spring diseases such as anthracnose, scab, rust, fire blight and black spot are appearing in landscapes throughout Kentucky. The severity of each of these diseases has been affected by temperature and moisture at the critical early growth stages when plants were susceptible to infections. From one location to another, the severity of these diseases varies greatly, because a) the weather has been variable statewide, and b) the plants may or may not have been at susceptible growth stages when weather was favorable for disease.

Anthracnose diseases. Sycamores in central Kentucky show symptoms of dead foliage associated with cankers at the base of dead shoots and twigs. Leaf blotch symptoms are not common. This suggests that the fungus was active during wet weather early in the spring when temperatures were cool. Unless we enter an excessively wet period in the coming weeks, it appears that sycamore anthracnose will not be as severe as it has been for the past three years. Shoots and twigs of maples in western Kentucky are also blighted due to anthracnose disease. Ash leaflets with dead blotches are dropping due to early spring anthracnose infections. We have also observed anthracnose on twigs of pagoda dogwood, Cornus alternifolia, which is considered resistant to dogwood (Discula) anthracnose. Although each of these diseases is called anthracnose, each is host-specific and caused by different fungi. Advise homeowners and landscape maintenance persons to do nothing now about anthracnose. Good tree care will help the infected trees to tolerate the disease.

Apple scab. Leaves of susceptible flowering crabapples are covered with velvety olive-green spots, the result of primary infections that occurred when leaves were still expanding. The velvety texture of the spots is due to the production of secondary spores or conidia, which will initiate infections on nearby emerging foliage any time the leaves are wet for at least 9-10 consecutive hours. If the trees are valuable, fungicides could be used to slow the spread of secondary infections to new growth that is still emerging. Where appropriate, advise clients to replant with disease resistant crabapples such as 'Louisa', 'Mary Potter', 'Molten Lava', or 'Prairiefire'.

Fire blight. Flowering pears, flowering crabapples, and apples are showing symptoms of fire blight in eastern, southern, and western Kentucky. In most cases, the disease began in the flowers and is spreading from dead flower/fruit spurs into the subtending branch. Secondary shoot blight symptoms are also occurring. Most infections began during favorable weather that occurred in April while trees were in flower. Trees in central and northern Kentucky were not yet in bloom during this first infection period. Some symptoms have developed from enlargement of pre-existing twig and branch cankers. By the time that clients actually notice fire blight, it is best to just let the disease run its course. Mark infected branches and be sure to prune them out in the winter when there is little chance of spreading the disease.

Cedar Rusts. Tiny rust-colored spots are appearing on the leaves of hawthorn (cedar-hawthorn rust) and apple (cedar apple rust), and on the flowers of hawthorn (cedar-quince rust). This is the pycnial stage of these rust fungi; later in the season, the spots will enlarge and the aecial stage of the fungi (which furnishes spores to infect nearby cedars) will be present. Although cedar-quince rust can kill small hawthorn twigs, it normally does too little damage to make special control measures necessary.

Rose black spot. Susceptible unsprayed roses are now showing distinct symptoms of black spot. Dark, circular spots with irregular edges first appear on green leaves. The spotted leaves soon turn yellow and drop from the plant. Badly diseased roses will often fail to produce abundant flowers. Continued black spot infections should occur from now until late fall, weakening highly susceptible plants. Promote improved air movement and sunlight penetration by thinning out the rose plants or pruning out overhanging tree branches. Given Kentucky's warm humid summer weather, it is often necessary to make weekly applications of a fungicide to reliably produce suitable flowers on susceptible roses.

Research by Dr. Monte Johnson, Dept. of Entomology, UK

Rating System:

0=No pest activity (0% damage) or Pest absent

1=Low pest activity (1 - 33% damage or 1 borer)

2=Moderatepest activity (34 - 66% damage or 2 borers)

3=Severe pestactivity (67-100% damage or 3 or more borers)

Cultivar	Avg Rating	Comments
Cornus florida (white)	2.0
C. florida 'Cherokee Chief'	1.5
C. florida 'Barton White'	1.4
C. florida 'Cloud 9'	1.1
C. kousa 'Milky Way'	2.1	3 plants dead out of 10:2 to borers
C. kousa 'National'	2.9	3 plants dead out of 10:all to borers
C. kousa x florida 'Galaxy'	2.1	4 plants dead out of 10:2 to borers
C. kousa x florida 'Constellation'	2.2	4 plants dead out of 10:0 to borers
C. kousa x florida 'Star Dust'	1.8	6 plants dead out of 10:1 to borers
C.mas 'Gold Glory'	.2	1 plant with moderate infestation

Date of assessment was May 28. Notable that all the plants (10) of the Cornus florida cultivars are surviving, with relatively low borer activity.

The C. kousa cultivars and the C. kousa x florida crosses experienced notable mortality, with the most severe borer activity on C. kousa . National. and C. kousa x florida . Constellation. .

Lowest borer activity was on C. mas . Gold Glory. (Cornelian Cherry) that has characteristics quite different from the other dogwoods.

By Mike Potter, Extension Entomologist

Emergence of two serious pests of ornamental trees, the dogwood borer and flatheaded appletree borer, should occur later this month. The dogwood borer is the most serious pest of ornamental dogwoods, especially stressed trees in full sun. Flatheaded appletree borers are major pests of nursery-grown red maples, flowering crabapple, and several other hardwoods, especially those that are newly transplanted or under stress. Mated females of both species fly to host trees and lay eggs on the bark.

Control . As with other wood borer species, the key to control is having a lethal residue of insecticide on the bark to intercept newly-hatched larvae before they burrow into the tree. Generally speaking, the optimum time for treatment will be shortly after Memorial Day. Lindane or Dursban are effective, and should be sprayed to runoff on the trunk and major limbs. For flatheaded appletree borer, a second application after 3 weeks may provide additional protection.

By Stephen Nameth & Jim Chatfield, Ohio State University

http://www.ag.ohio-state.edu/~ohioline/hyg-fact/3000/3064.html

Ground cover plants are often planted in areas where weed control or masses of color are necessary. Ground covers are also used in areas where conditions are such that grass or other plants will not grow. Environmental stress factors associated with such sites can favor certain infectious diseases. The major diseases of ground cover plants and their controls are described below.

Leaf Blight and Stem Canker of Pachysandra

Leaf and stem canker are caused by the fungus, Volutella pachysandricola. The leaves of affected plants at first develop brown, target-like blotches on them, often on areas of the leaves previously damaged by stresses such as sunscorch. They later become generally blighted. Stem cankers and blackish discoloration will develop and cause a die-back of the plants. Cankers may be located anywhere on the stem. When conditions are moist for extended periods, orangish-pink spore masses of the Volutella fungus may develop. Circular, spreading areas of diseased plants will be noticeable in the planting. The disease will be especially severe when plants are crowded and weather is wet.

Fungicides containing copper (Phyton 27, Kocide), Thiophanate-methyl + mancozeb (Zyban, Duosan), chlorothalonil (Daconil 2787), and mancozeb (FORE) are labeled for control of this disease. Spray affected plants every two weeks from bud break in the spring until plant growth slows in mid or late summer. Cultural control measures (described below) are also important.

Canker and Die-Back of Vinca

The fungi causing this disease (Phoma sp. and Phomopsis sp.) cause the shoot tips to become dark brown, wilt, and die back to the surface of the soil. Some affected stems are black in color. Small, black, dot-like, fruiting bodies develop on the surface of the diseased stem tissue.

Wet weather or frequent overhead watering favors the disease. Cultural control (see below) is very important. For chemical control, some copper (Phyton 27, Kocide) or mancozeb (FORE) containing fungicides are labeled and can be used according to labeled instructions. Spray affected plants once a month from bud break in the spring until plant growth slows in mid or late summer.

Bacterial Leaf Spot of English Ivy

Leaf spots, caused by the bacterium Xanthomonas campestris pathovar hederae, will appear light green and watersoaked (oily) at first. Later, they enlarge and become dark brown or black. The watersoaking will still be evident on the edge of the spot. This is especially visible when viewed from the leaf undersurface. Petiole and stem cankers may develop, causing leaf yellowing and shoot die-back.

Wet weather or frequent overhead watering, particularly in the evening, favors the disease. A fixed copper spray (Phyton 27, Kocide) can be used for control. Copper fungicides may be toxic to some English ivy. If in doubt, treat only a few plants and wait 2 days to check for damage. Follow the cultural control practices mentioned below.

Crown Rot of Ajuga

The crown rot fungus, Sclerotium rolfsii, infects the plants and causes a sudden wilting and death. Examination of wilted plants reveals that the stem is rotted near the soil. During hot, humid weather a white mold growth may be seen on the stem or ground around the stem. Later, small tan resting bodies of the fungus will form on the stem. These resting bodies look almost exactly like mustard seeds.

Diseased plants must be removed to prevent further spread. Remove the plants and four to five inches of surrounding soil, and drench the bare spot with PCNB (Terraclor) fungicide before replanting. Follow the labeled instructions for use. Be sure to follow the cultural control practices outlined below.

Cultural Control Measures for Infectious Groundcover Diseases

Infectious plant diseases are best managed via an integrated approach employing many strategies. Some of these strategies are aimed toward sanitation and removal of infected plant tissue or the pathogen. Other strategies are aimed at enhancing the vigor and natural resistance of the plants.

1. Always select and plant high quality plant material. Select plants that are growing well and are free of nutritional deficiencies. If any disease is noted in the plants, do not purchase them.

2. For established beds, remove infected plants and prune out diseased parts of plants. Discard or burn infected material.

3. Thin planting to remove dense growth. Thin in fall during dry weather.

4. Fertilize appropriately to maintain plant vigor. If excess fertilization causes dense growth, plants may need to be thinned.

5. Remove dead leaves and other accumulated plant debris. Do this very early in the spring.

6. Water to prevent weakened, drought stressed plants. Water early in the day so that drying occurs before evening. Avoid splashing of water.

7. Use fungicides as already mentioned above. Spray to thoroughly wet the plants. Use a spreader-sticker spray additive if the fungicide you have selected is a powder. Many of the products mentioned above may not be available in small packages for home landscape use. If such is the case, home horticulturists should contract a professional plant care service to make the applications.

By John Hartman, Extension Plant Pathologist

In many areas of central Kentucky, white pines, especially those growing in Christmas tree plantations and nurseries, are now showing symptoms of browning and premature loss of last year's needles. This has left many trees quite bare, with the only foliage remaining being the needles emerging from the still-elongating candles. On affected trees, clumps of dead needles are easily combed out of the branches and although most of the needles are brown, a few that have not yet completely desiccated are still a faded green color with bands of yellow. The trees themselves are still very much alive and the newly emerging needles are healthy. Thus, in a few weeks, the trees could appear to be fairly healthy, but with foliage less dense than normal.

Based on site visits in Fayette and Clark Counties and laboratory specimens from Woodford and Shelby Counties, the problem is appearing over a widespread area in central Kentucky. Within the individual plantings, perhaps 10-25% of the trees are affected and the severity of the affected trees varies from almost complete defoliation to loss of perhaps half of last year's needles. Affected trees would not be attractive specimens for transplanting now, and even with new needle growth, lack of density may make these trees unattractive for Christmas sales as well.

What is causing defoliation of these white pines? It is likely that this problem stems from an air pollution event sometime in the latter part of last summer. The symptoms we are seeing are typical of oxidant air pollutants such as ozone. Injury to pines often occurs during warm weather when pollutants accumulate in stagnant air. The yellow banding of needles may be inconspicuous during the growing season but the problem often intensifies during the winter and spring in the form of browning and defoliation. Since these pollutants are not usually confined to a small area, one would expect symptoms to appear over a wide area of the state. Although the exposure was general, not all trees within a field were affected. This variation within a planting reflects genetic differences between trees grown from seedlings and it is normal to see these different responses to air pollution damage within a population of white pines.

When did the air pollution event(s) occur? The following information is based on consultations with Tom Priddy, our U.K. Agricultural Meteorologist and information obtained by him from Jerry Suddath at the Kentucky Department of Air Quality. Air quality standards (ozone more than 0.08 ppm for 8 hours or longer) were exceeded in 1998 in central Kentucky on August 7, and September 4-6 and 12-13. A brief, but potent hourly episode of 0.75 ppm on October 16 may also have contributed. For sensitive plants, daily averages of 0.05 ppm or hourly exposures of up to 0.1 ppm are sufficient to cause symptoms. Thus, our best guess of when the damage we are seeing now originated is late last summer. Although conditions for a few warm days in December were also favorable for air stagnation, readings were not taken then, and it is generally thought that pines are not sensitive to air pollution during the dormant season.

What is the prognosis for affected white pines? The affected trees are not dead or even dying. They will undoubtably be growing under stress, at least until the new needles are fully functioning, and even then they will have fewer energy reserves than unaffected trees. Growers will need to be sure that the affected trees receive adequate water through the season and that infectious diseases, insect pests, and weeds are managed. For now, affected trees will not be as marketable as they would have been, but perhaps will be back to normal in another year.
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