Fruit Pest News
Volume 3, No. 14 June 10, 2002
A weekly, online newsletter whose goal is to update Extension agents and growers of commercial tree fruit and small fruit crops
on diseases and insects in Tennessee.
Text appearing in blue or red can be clicked to link to other web sites. Be aware that much of the linked information is produced in other states and may not be applicable to Tennessee.
In This Issue:
1. Tree Fruit: Plant Bugs and Green Stink Bugs
2. Apple: Summer Disease Control Program
3. Blackberries: Continue to Watch for Rosette
4. Pesticide and Fertilizer Security -- Priority No. 1
1. Tree Fruit: Plant Bugs and Green Stink Bugs
Plant bugs are
true bugs (Order Hemiptera) in the family Miridae. They have piercing-sucking mouthparts
and their feeding and oviposition can cause damage to fruit or foliage. Tarnished
plant bugs are small (4.9 -5.7 mm), brownish and mottled with shades of yellow and
reddish brown. They feed on a large number of plants including wild mustard and other
flowers, tobacco, cotton, some field crops, vegetables, and tree fruit. In apple,
the overwintered adult bugs move to apple buds around delayed dormant bud stage.
They lay eggs in the blossom buds beginning when the blossoms in the clusters begin
to separate. They continue to feed and lay eggs until the fruit are 1/2 inch in diameter.
The feeding punctures cause tiny indentations and distortions of the fruit. There
is a complex of plant bugs that can attack apples. These include the apple redbug,
green apple bug, dark apple redbug and the mullein leaf bug. Some cause a conical
indentation in the fruit without russeting or corky tissue, such as the tarnished
plant bug. Others produce corky indentations or even long corky scars due to repeated
feeding tracks. Since the feeding or oviposition damage is done early in the fruit
development, there is nothing that can be done to reverse the damage. Fortunately,
much of the feeding damage, especially the indentations without russeting or corky
tissue, is overlooked when grading the fruit.
The tarnished plant bug is
the major pest of peaches although the oak plant bug, the hickory plant bug and the
green stink bug (Pentatomidae) can be damaging. The general injury categories are
blossom injury and fruit drop, cat-facing injury, scarred injury, water-soaked injury
and gummosis. Blossom injury, fruit drop and cat-facing are the most damaging. Blossom
injury and fruit drop include feeding damage causing blossom drop, and feeding damage
between petal-fall and shuck-off causing fruit drop. About one third of blossom
drop can be caused by tarnished plant bug.
Cat-facing deformities are caused
by feeding between the shuck-split stage and 20 mm diameter fruit. Cat-facing damage
consists of depressions that are covered with brown, corky tissue, predominately
free of fuzz. There is usually a mass of gum at the center of the injured area. The
fruit attacked early usually drop while that injured later (diameter greater than
20 mm) will be scarred but remain on tree.
Typical scarred injury consists
of small (1-2 mm) brown, corky, fuzz free areas sometimes with a red pigment in the
skin around the edge of the scars. When numerous, these small scars can blend to
form 9 by 25 mm scarred areas.
Water-soaked injury consists of small dark
green areas that appear water-soaked. They are round and 2-3 mm in diameter. Gummosis
is the oozing of clear gum from insect feeding punctures.
Monitor for plant
bugs by hanging reflecting, white rectangular sticky traps 3 feet from the ground.
Hang the traps along the edge of a block preferably near wooded areas. Hang 3 traps
per block or one trap for every 3-5 acres. Start monitoring at Pink and continue
until mid-summer. The threshold for peach is one plant bug per trap.
The
green stink bug causes sunken areas or pits that can badly deform the fruit. Much
of the damage occurs late in the summer as shallow, water-soaked depressions. You
can monitor for green stink bugs by jarring the branches over a ground cloth (sheet)
or beating tray. I referred to "Common Tree Fruit Pests" by Angus H. Howitt
for much of the information on plant bugs and green stink bugs. (FAH)
2. Apple: Summer Disease Control Program
Your summer disease control program is, no doubt, well underway. The so-called summer diseases take a greater toll on Tennessee apple production than the spring diseases. The summer diseases are fueled by a continuing source of overwintered inoculum, and there are fewer effective fungicides from which to choose. Furthermore, it is more difficult to obtain good spray coverage during the summer than during the spring because of more dense foliage, fruit clustering, and limbs drooping under heavy crop loads.
Your choice of fungicides will depend to some extent on what diseases have historically been a problem in your orchard. If bitter rot has been a problem, captan should be a major component of your summertime spray program (Note: I have already spotted some bitter rot). Flint also performs well against bitter rot. If white rot has been a problem, captan or a benzimidazole (Benlate, Topsin M) should be relied on heavily. For sooty blotch and flyspeck, be sure to include a benzimidazole or a strobilurin (Flint, Sovran). Strobilurins are also a valuable component of a program if scab is still active, as they are very effective against fruit scab. In Golden Delicious blocks, it is a good idea to include ziram or thiram to help protect against necrotic leaf blotch. Mancozeb provides good control of most summer diseases, but cannot be used within 77 days of harvest when used at the 3/4 lb per 100 gallon rate.
Keep in mind the 4-day re-entry interval for captan. Where this is a problem, consider using ziram instead. In such cases, ziram should be mixed with a benzimidazole for improved control of black rot and white rot. Remember that management of diseases with fungicides is improved if cultural practices that reduce inoculum and enhance coverage are used. (SB)
3. Blackberry Rosette: Continue to Watch for It
Rosette (double blossom) disease is the scourge of blackberries. It has the potential to destroy a blackberry planting. If it is present in your planting, it should be readily apparent as bare berry caps; i.e. berries that do not develop. Click here for an image. The sepals (the green, leaf-like structures that enclose blossoms) are abnormally long and pointed and may have a pink to purplish color. The infected fruit clusters usually consist of multiple shoots, rather than the normal single shoot. Such growths are known as rosettes or witch's brooms.These rosettes should have been removed in the spring, before the blossoms opened, releasing the spores. Removing and destroying the rosettes now would still be worthwhile, since some spores are still being released. The fungus is not systemic in the plant, so only the side stems showing disease symptoms have to be removed. Use Benlate or copper at 10-14 day intervals. However, do not expect fungicide applications to control rosette in this year's crop. Fungicides applied this year control rosette in next year's crop by protecting the new primocanes. Any rosettes you see this year arose from infections that occurred on primocanes last year.
Fungicidal control may have a place even if you do not currently have rosette, if you are growing a susceptible variety. Shawnee, Cherokee, Comanche, and Black Satin are examples of very susceptible varieties. (SB)
4. Pesticide and Fertilizer Security -- Priority #1
by Gene Burgess, University of Tennessee entomologist
Dealers should keep pesticide and fertilizer security
as a high priority. It is easy to drop our guard when things quiet down. But the
danger still exists. An occurrence in Illinois should serve as a strong reminder
- "Security is Priority #1": The following alert was issued by the Illinois
Fertilizer and Chemical Association (IFCA) following an attempt by an
unauthorized individual to gain access to a commercial agricultural chemical
retail facility. The following alert was written by Jean Trobec, IFCA's Director
of Government Relation, and should remind all agribusiness retailers of the
importance of facility security.
Security Alert ? Person Poses As IDA Inspector
An IFCA member in central Illinois reported that a clean-cut young man entered one of their facilities last week, presented himself as a new inspector from the Dept of Ag and asked to inspect the chemical building. The IFCA member had a policy requiring all persons visiting the facility to sign in, and asked the man to do so. He hesitated, said he had to get something out of his truck, and then drove away. The manager noticed the truck had no front plate and only a temporary plate in the back. He immediately reported the incident to law enforcement and the IL Dept of Ag. This dealer's policy to require ID from all persons entering the facility no doubt thwarted a theft or something more sinister. With the emphasis on homeland security, the fertilizer and chemical industry must be responsible. Be sure you enact the following principles at your business:
Know your customers! Who you are selling to and who you are giving information to over the telephone.
Require ID from anyone who says they are from a government agency and wants to perform an inspection. A legitimate inspector won't have a problem producing ID.
Make all visitors sign in at the main office. Accompany visitors while they are at the facility.
Do a walk-around of your facility each morning and check for signs of theft or tampering. Report thefts and suspicious activity immediately.
Keep all buildings locked, and remove the keys from your application equipment at the end of the day.
Be aware, and be secure! The USDOT is proposing that all companies who transport hazardous materials have a written security plan, and it is likely that this will become law. Just another example of the major responsibility our government is placing on us to keep our products secure, prepare ourselves against the unthinkable, plan for emergencies and take precautions to avoid intentional misuse of our products.
The Fruit Pest News URL is: http://web.utk.edu/~extepp/fpn/fpn.htm
Contacts:
Steve Bost, Professor and Extension Plant Pathologist
Frank Hale, Associate Professor and Extension Entomologist
Both authors available at:
615-832-6802
fax 615-781-2568
Plant and Pest Diagnostic Center
5201 Marchant Drive
Nashville, TN 37211