Fruit Pest News
Volume 8, No. 12 May 29, 2007
A weekly, online newsletter whose goal is to provide all interested persons with timely information on diseases and insects of commercial fruit and vegetable crops 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. Current Conditions
2. Vegetable Pest Update
3. Fire Blight: Managing Affected Trees
4. Tree Fruit Pest Updates
5. IR4 Launches Searchable Database for Biopesticides and Organic Products
6. Possible Cancellation of Chloroneb
7. Fabraea Leaf Spot Control on No-Fruit Pear Trees
8. Pheromone Trap Catches
1. Current Conditions
Moisture deficits are reaching critical levels in some areas. On the bright side, the dry conditions should reduce the disease risk for tree fruit growers who have decreased their spray intervals for economic reasons where fruit are lacking. Unless specific pest problems are noted, spray intervals may be stretched to 4 weeks. Scout the orchard closely when following such a schedule. Intervals of 2 weeks may be needed when pest problems are observed; e.g., efforts to control powdery mildew with sulfur would probably require 2-week intervals. (SB)
2. Vegetable Pest Update
Colorado potato beetle adults
overwinter in weedy areas around potato, pepper, tomato, and eggplant fields. Since
they crawl back into the fields to lay eggs on the host plants in the spring, one
way to limit damage is to not plant a solanaceous crop in the same field two years
in a row. A systemic insecticide such as imidacloprid (Admire and other brands)
and thiamethoxam (Platinum) can be used preventatively by a number of application
techniques. For potatoes, seed pieces can be treated with imidacloprid prior to
planting or while in the furrow. If a systemic insecticide is used as a preventative
treatment, do not apply a foliar spray with the same active ingredient (thiamethoxam
[Actara], imidacloprid [Provado]) for resistance management purposes. If a systemic
insecticide was not used, plants can be treated with spinosad (SpinTor) and other
recommended foliar applied insecticides. Try to target Colorado potato beetle eggs
at hatch or soon after to control small larvae.
Squash bugs are also best
controlled early, especially so now that their link to yellow vine disease has been
established. Spray early to prevent the overwintered adult squash bugs from feeding
and laying eggs.
Flea beetles can become an early season problem on eggplant,
potatoes and tomatoes. Protect young plants with timely sprays. Bean leaf beetles
chew many holes in the leaves of emerging bean seedlings. Apply a protective insecticide
spray to young plants if there is a high potential for serious defoliation.
Potato
leafhoppers are tiny light green flying insects that suck sap from the veins on the
underside of leaves of alfalfa, potato, rhubarb, dahlia, eggplant, and red maple.
Its feeding on the phloem cells causes them to become torn, distorted and the xylem
tubes to become plugged. The leaf tips turn brown or the entire brown margin of
the leaf can become brittle and cup inward or upward, depending on the plant. This
hopperburn often appears like a rapidly occurring drought stress. Systemic insecticides
are especially effective and tend to be more long lasting. (FH)
3. Fire Blight: Managing Affected Trees
Following are some reminders for management of fire blight at this time of year. Efforts to limit secondary spread by cutting out fire blight strikes are most successful if the strikes are removed immediately after they appear. By this time in Tennessee, it is too late for strike removal to effectively reduce the rate of spread of the epidemic. Pruning of fire blight shoots during the growing season should be limited to light to moderate cases. Extensive pruning of heavily blighted trees is neither practical nor desirable, as the result would be the stimulation of new, succulent tissue, which is very susceptible. However, young trees and high density, dwarf-tree orchards should be followed closely and strikes should be removed immediately, regardless of the severity of the outbreak. In such trees, the infection can spread internally to the rootstocks and cause tree death.
Classical recommendations for growing-season removal of fire blight strikes include making the cut 8 to 12 inches below the blighted area and sterilizing the pruning tool between each cut. We now know that this approach has limited effect because of the systemic nature of the bacterial infection. If the infected shoot is associated with the main trunk or a major scaffold limb, you may want to try the "ugly stub" cut, leaving a two-inch stub for winter removal.
Other practices to keep in mind: Excessive tree vigor should be discouraged. Use management systems that promote early cessation of tree growth without adversely affecting tree vigor. Maintain good control of sucking insects, as some of them can transmit the causal bacterium to healthy shoots. If you prune, remove and destroy fire-blighted shoots and limbs, since they can serve as a source of inoculum. If the amount cut cannot be removed quickly, there may be too much blight present for the cutting operation to be effective. (SB)
4. Tree Fruit Pest Updates
While redbanded leafrollers are one of the earlier
moths caught in pheromone traps, interestingly they are more of a late summer pest
problem. This pest has several generations and is usually only a sporadic problem.
The last generation moth generally lays eggs from mid-August to mid-September.
Feeding on the outer skin of the maturing fruit can be damaging while webbing leaves
over fruit will prevent the covered area from developing its mature color.
Dogwood
borer is a serious pest of apple trees. Apply insecticides (Lorsban 50 W, Lorsban
4E, Asana XL) with a handgun sprayer to the trunk, especially to burr knots and graft
unions. Spray Lorsban from close range (no more than 4 feet away) with a shielded
sprayer to prevent drift onto foliage or fruit. In Tennessee, dogwood borer moths
have a peak emergence in late April and continue to emerge with a second peak emergence
in mid-July. Treatment before July is optimal.
According to Henry Hogmire
in the May 14 edition of The Orchard Monitor newsletter, several cultural practices
can help reduce dogwood borer damage. He cautions against using plastic spiral tree
guards that prevent insecticide spray from contacting the lower trunk. Use porous
tree guards instead. Also the development of burr knots can be reduced with good
weed control around the trunk This practice reduces the shade and increased humidity
that tends to promote burr knot formation. Another helpful practice is to mound
soil around the burr knots on the exposed rootstock up to the graft union. Take
care not to cover the graft union in order to prevent the formation of roots from
the scion. (FH)
5. IR-4 Launches Searchable Database for Biopesticide and Organic Products
Biopesticides are becoming increasingly numerous and increasingly important in crop production. The following is from an IR-4 Project Press Release:
The Interregional Research Project No. 4 (IR-4), has announced the launch of its Biopesticide / Organic database on the IR-4 website. The database, which is searchable by crop, pest, and state, will assist commercial and home growers of specialty crops. Specialty crops include fruits, vegetables, ornamentals and turf, but IR-4 also includes minor pests that are found on major row crops in this database. IR-4 Biopesticide Manager, Dr. Michael Braverman explained, “This project was conceived out of the observation that most growers or homeowners were unaware of the variety of today’s biopesticides. There are a few Biopesticides that show up on conventional product websites, but there isn’t a database for just biopesticides and organics. Creating this database is a tool for helping growers find answers to their pest problems.”
Locate the database at www.ir4.rutgers.edu/Biopesticides/LabelDatabase/index.cfm and click on the “Find Answers” prompt. Once opened, the database enables growers to input their crop, pest and state and it responds by providing a list of EPA registered product labels that fit their criteria.
Biopesticides are primarily natural products or organisms that are compatible with integrated pest management. They have broad modes of action, which avoids resistance problems that may exist with some conventional products. Biopesticides often work best in rotation with conventional products so that optimal pest management can be obtained. Most biopesticides have no restricted entry interval requirements, whereas conventional products often limit the time growers can return to the fields following a treatment.
6. Possible Cancellation of Chloroneb
Chloroneb (Nu-Flow D) is a vegetable seed treatment used to control Rhizoctonia seedling diseases. The EPA has issued the following statement regarding chloroneb fungicide:
The EPA is issuing a notice of receipt of a request by the registrant to voluntarily terminate certain uses of its chloroneb products. The request would terminate chloroneb's use on all seed treatment. The request would not terminate the last chloroneb product registered in the United States. EPA intends to grant this request at the close of the comment period for this announcement unless the Agency receives substantive comments within the comment period that would merit its further review of the request, or unless the registrant withdraws its request within this period. Comments must be received on or before June 25, 2007.
Refer to the following site for information on how to comment: http://www.epa.gov/EPA-PEST/2007/May/Day-25/ (SB)
7. Fabraea Leaf Spot Control on No-Fruit Pear Trees
The lack of fruit on pear trees this year provides a good opportunity to control Fabraea (Entomosporium) leaf spot. Research at Cornell University has shown that mancozeb is the most effective fungicide for control of this destructive disease. In most years, mancozeb's use is limited by the lengthy preharvest interval of 77 days -- Not a problem this year unless you are lucky enough to have fruit on your trees. By using mancozeb, you should be able to obtain adequate control of Fabraea while minimizing your number of pear sprays. At 3 lb per acre, up to 7 sprays per year are allowed by the label. (SB)
8. Pheromone Trap Catches for 2007
Nashville
(Davidson County)
Oriental fruit moth (OFM), redbanded
leafroller (RBLR), obliquebanded leafroller (OBLR), codling moth (CM), grape berry
moth (GBM), variegated leafroller (VLR), black cutworm (BCW), diamondback moth (DBM),
armyworm (AW), cabbage looper (CL)
| OFM | RBLR | OBLR | CM | GBM | VLR | BCW | DBM | AW | CL | |
| 2-22 (caught one RBLR in last year's trap) put out new trap | -- | 1 | -- | -- | -- | -- | -- | -- | -- | -- |
| 2-26 | -- | 0 | -- | -- | -- | -- | -- | -- | -- | -- |
| 2-28 | -- | 1* | -- | -- | -- | 1 | -- | -- | -- | -- |
| 3-2 | -- | 3 | -- | -- | -- | 0 | -- | -- | -- | -- |
| 3-12 | -- | 50 | 0 | -- | -- | 0 | -- | -- | -- | -- |
| 3-14 (Put out OFM, CM, OBLR, BCW) | -- | 26 | -- | -- | -- | 0 | -- | -- | -- | -- |
| 3-20 | 0 | 33 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 3-21 | 1 | 7 | 0 | -- | -- | 0 | 0 | -- | -- | -- |
| 3-26 | 20** | 34 | 0 | -- | -- | 0 | 0 | -- | -- | -- |
| 3-27 (put out AW trap) | 8 | 4 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 3-30 | 12 | 16 | 0 | 0 | -- | 0 | 0 | -- | 0 | -- |
| 4-2 | 18 | 18 | 0 | 0 | -- | 0 | 0 | -- | 1 | -- |
| 4-3 (put out DBM, GBM, CL) | 10 | 1 | 0 | 0 | -- | 0 | 0 | -- | 0 | -- |
| 4-5 | 11 | 0 | 0 | 0 | 4*** | 0 | 0 | 0 | 0 | 0 |
| 4-10 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-17 | 2 | 1 | 0 | 0 | 2 | 0 | 0 | 0 | 0 | 0 |
| 4-23 | 28 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-25 | 8 | 0 | 2**** | 0 | 0 | 0 | 0 | 4^ | 0 | 0 |
| 4-30 | 5 | 0 | 6 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| 5-21 | 3 | 2 | 6 | 0 | 0 | 0 | 0 | 4 | 5 | 5 |
| 5-29 | 6 | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
* Biofix for RBLR in Davidson County was February 28.
** Biofix for OFM in
Davidson County was March 26.
*** Biofix for GBM in Davidson County was April
10.
**** Biofix for OBLR in Davidson County was April 25.
^ Biofix for DBM
in Davidson County was April 25.
Bradley County
| OFM | CM | |
| 3-26 | 1 | 0 |
Putnam County Pheromone Trap Catches for 2007
| OFM | RBLR | OBLR | CM | VLR | |
| 3-19 | 1 | 9* | 0 | 4*** | 0 |
| 3-21 | 1** | 3 | 0 | 2 | 0 |
| 3-23 | 2 | 6 | 0 | 1 | 0 |
| 3-26 | 2 | 15 | 0 | 2 | 0 |
| 3-28 | 4 | 7 | 0 | 1 | 0 |
| 3-30 | 2 | 14 | 0 | 0 | 1 |
| 4-2 | 6 | 32 | 0 | 0 | 0 |
| 4-6 | 2 | 28 | 1 | 1 | 0 |
| 4-13 | 0 | 2 | 1 | 0 | 0 |
| 4-20 | 0 | 7 | 0 | 0 | 0 |
| 4-23 | 0 | 1 | 1 | 2 | 1 |
| 4-25 | 0 | 0 | 1**** | 0 | 0 |
| 4-27 | 0 | 1 | 3 | 0 | 0 |
| 5-4 | 0 | 1 | 5 | 6 | 2 |
| 5-11 | 0 | 15 | 0 | 0 | 1 |
| 5-25 | 0 | 24 | 0 | 0 | 0 |
*Biofix for RBLR in Putnam County estimated as March 2 (trap not out early enough).
**Biofix
for OFM in Putnam County March 21.
***Waiting to verify biofix for CM, many unknown
moths being caught in these traps that can easily be mistaken for CM.
**** Biofix
for OBLR in Putnam County for OBLR was April 25.
Obion County
| OFM | RBLR | OBLR | CM | VLR | |
| 3-19 | 0 | 17* | 0 | 0 | 0 |
| 3-26 | 5** | 89 | 0 | 1 | 0 |
| 4-11 | 0 | 0 | 0 | 0 | 0 |
| 4-16 | 2 | 0 | 0 | 0 | 0 |
| 4-23 | 0 | 0 | 0 | 0 | 1 |
| 4-30 | 7 | 0 | 10*** | 0 | 17**** |
| 5-7 | 10 | 0 | 3 | 0 | 2 |
| 5-17 | 11 | 3 | 7 | 1 | 14 |
| 5-21 | 0 | 7 | 1 | 0 | 5 |
| 5-29 | 0 | 5 | 0 | 0 | 0 |
* Biofix for RBLR in Obion County estimated to be on March 2 (trap not out early
enough).
** Biofix for OFM in Obion County on March 26.
*** Biofix for OBLR
in Obion County on April 30.
**** Biofix for VLR in Obion County on April 30.
The Fruit Pest News URL is: http://web.utk.edu/~extepp/fpn/fpn.htm
Contacts:
Steve Bost, Professor and Extension Plant Pathologist
Frank Hale, 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
Copyright 2007 The University of Tennessee. All rights reserved. This document may be reproduced and distributed for nonprofit educational purposes provided that credit is given to University of Tennessee Extension.
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