Fruit Pest News
Volume 9, No. 16 September 4, 2008
An 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 Situation
2. Soil Fumigant Changes and a Strawberry Grower Survey
3. Choanephora Pod Rot of Southern Pea
4. Cucurbit Yellow Vine Disease
5. Grape Root Borer Pheromone Trap Catches
6. Other Pheromone Trap Catches
7. Insecticide Updates for the Vegetable Crop Handbook
1. Current Situation
General: Diseases have been rather quiet, for the most part, due to the dry weather this summer. That picture could change now that we are in an active tropical storm season. You have probably been on a reduced spray program because of the low disease pressure, but be prepared to tighten the spray schedule now. Use a broad-spectrum protectant fungicide before a low-pressure weather system reaches you, bringing high disease pressure.
Cucurbits: Because of the threat of downy mildew, growers of cucurbit crops should purchase and be prepared to use some Ranman, Presidio, Curzate, Previcur Flex, or Tanos. The usual protectant fungicides (chlorothalonil, mancozeb) are not very effective against the new strain of downy mildew, but should be used because of their broad-spectrum disease protection. Although no downy mildew has been reported in the state this year, that could change, especially in West TN, where Hurricane Gustav visited that past couple of days. The winds may have brought spores up from the sources in Louisiana. The known downy mildew sources can be found at this web site. (SB)
2. Soil Fumigant Changes and a Strawberry Grower Survey
This is just a reminder of the changes coming in the way we apply soil fumigants, and that the comment period has been extended to October 30. The EPA has determined that the fumigants are eligible for reregistration, but only if risk mitigation measures are implemented to increase protection for workers and bystanders. Changes include requirements for buffer zones, reporting and recordkeeping, and worker protection, including the use of respirators. The comment period deals with implementation of the regulations. For details of these measures and instructions on how to comment, see the fumigant web page at: http://www.epa.gov/pesticides/reregistration/soil_fumigants/index.htm .
Strawberry growers may be interested in participating in a survey that will help the North Carolina Strawberry Association prepare comments on behalf of growers in our region. The survey is posted at http://www.ncstrawberry.org/docs/FumigantsQUERYAug2008-A.pdf . They need your response soon. (SB)
3. Choanephora Pod Rot of Southern Pea
In a small field of southern peas in West Tennessee last week, most pods were destroyed by pod blight, caused by Choanephora cucurbitarum. Also known as wet rot, blossom blight, and whisker rot, this disease is common on squash, southern pea, and okra, but occurs on the floral parts of many types of plants.
The fungus is a rather weak pathogen, as it enters the plant through spent flower parts. In southern peas, puncture wounds from the cowpea curculio provide additional avenues of entry. The dark gray to black mold appears first on flower parts, then moves into the fruit under wet conditions. On southern peas, the rot is usually found at the point of attachment of the pod to the stem and, in wet weather, can move down the stem.
Fungicides are not very effective against this disease, but losses are usually minimal unless air drainage is poor. Site selection is the most important factor determining the severity of wet rot. Avoid low-lying, tree-lined fields where restricted air movement allows a buildup of humidity and limits drying opportunities after wetting events. If such sites cannot be avoided, strict attention to other preventive practices are necessary. Avoid crowded plant populations and high nitrogen fertilization, which can cause excessive growth. On southern pea, maintain control of the cowpea curculio. Varieties that tend to lodge favor high populations of curculio and problems with pod blight. Use erect varieties in which the pods have good ground clearance. Avoid harvesting and storing green pods under wet conditions. (SB)
4. Cucurbit Yellow Vine Disease
Some bright yellow leaves have been spotted in otherwise green pumpkin fields lately. A bacterial disease called cucurbit yellow vine disease (CYVD) has been implicated in some of these cases. CYVD is transmitted by squash bugs, and they have been plentiful this year. Symptoms of the disease are yellowing and a gradual decline of the vine, usually occurring in spots in the field. Since other factors can also cause these symptoms, diagnosis of CYVD depends on the presence of a honey-brown discoloration of the phloem ring, as seen by slicing through the stem near the ground. Most cucurbit crops are susceptible to CYVD, with cantaloupe, watermelon, and pumpkin being the most notable. Control of the disease is by control of the squash bug vector. (SB)
5. Grape Root Borer Pheromone Trap Catches
A
pheromone trap put out for the squash vine borer usually catches many more grape
root borers than squash vine borers at the Nashville location. Both of these insects
are closely related clearwing borer pests. This summer, zero squash vine borers
were caught in the trap but grape root borers were caught on July 23 (2 moths), August
21 (24 moths) and September 3 (31 moths). A prolonged emergence is common for many
of the clearwing borer moths which can make control more difficult. (FH)
6. Pheromone
Trap Catches and Biofixes (FH)
Nashville (Davidson County) Pheromone Trap
Catches for 2008
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)
| OFM | RBLR | OBLR | CM | GBM | VLR | BCW | DBM | AW | CL | |
| 3-10 (Put out RBLR trap) | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-13 | -- | 2* | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-19 | -- | 5 | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-31 | -- | 7 | -- | -- | -- | -- | -- | -- | -- | -- |
| 4-1 (put out BCW, OFM, CM, VLR, OBLR traps) | ||||||||||
| 4-9 | 0 | 2 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 4-11 (put out AW trap) | 2** | 0 | 0 | 0 | -- | 0 | 0 | -- | -- | -- |
| 4-17 (put out GBM, DBM, CL traps) | 0 | 0 | 0 | 0 | -- | 0 | 0 | -- | 0 | -- |
| 4-18 | 1 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-24 | 2 | 0 | 0 | 0 | 3*** | 0 | 0 | 0 | 0 | 0 |
| 4-29 | 2 | 16 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 5-12 | 6 | 0 | 3^ | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-20 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-27 | 1 | 6 | 17 | 0 | 0 | 0 | 0 | 2 | 0 |
0 |
| 6-2 | 2 | 6 | 8 | 0 | 0 | 0 | 0 | 1 | 0 | 2^^ |
| 6-10 | 3 | 3 | 13 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 6-16 | 0 | 0 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
| 6-24 | 1 | 2 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| 7-23 | 1 | 2 | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 8-21 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 9-3 | 4 | 0 | 7 | 3 |
* Biofix for RBLR in Davidson County was March 13.
**Biofix for OFM in Davidson
County was April 11.
***Biofix for GBM in Davidson County was April 24.
^Biofix
for OBLR in Davidson County was May 12.
^^Biofix for CL in Davidson County was
June 2.
Bradley County Pheromone Trap Catches for 2008
tufted apple bud
moth (TABM)
| 3-18 (put out OFM trap) | OFM | CM | TABM |
| 4-6 (put out CM trap, TABM) | 0 | -- | -- |
| 4-12 | 0 | 1 | 4 |
| 4-14 | 0 | 0 | 2 |
| 4-19 | 0 | 1 | 0 |
| 4-21 | 0 | 0 | 23 |
| 4-29 | 1 | 5 | 14 |
| 5-5 | 0 | 2 | 5 |
| 5-11 | 0 | 2 | 13 |
| 5-19 | 0 | 1 | 23 |
| 5-26 | 0 | 0 | 8 |
| 6-2 | 0 | 0 | 3 |
| 6-9 | 0 | 0 | 5 |
| 6-16 | 0 | 0 | 0 |
| 6-23 | 0 | 0 | 0 |
| 6-30 | 0 | 0 | 0 |
Putnam County Pheromone Trap Catches for 2008
| 3-16 (put out RBLR, OBLR, VLR) | OFM | RBLR | OBLR | CM | VLR |
| 3-21 | -- | 12* | 0 | -- | 0 |
| 4-1 | -- | 5 | 0 | -- | 0 |
| 4-9 (put out OFM, CM) | -- | 7 | 0 | -- | 0 |
| 4-13 | 0 | 0 | 0 | 0 | 0 |
| 4-22 | 0 | 9 | 0 | 0 | 0 |
| 4-29 | 0 | 0 | 0 | 0 | 0 |
| 5-4 | 0 | 0 | 0 | 0 | 0 |
| 5-13 | 0 | 0 | 10** | 0 | 0 |
| 5-20 | 0 | 0 | 30 | 0 | 0 |
*Biofix for RBLR in Putnam County estimated as prior to March 21 (trap not out
early enough).
**Biofix for OBLR in Putnam County was May 7.
Obion County
Pheromone Trap Catches for 2008
*Biofix for RBLR in Obion County was March 28
**Biofix
for OFM in Obion County was April 21
***Biofix for OBLR for Obion County was
May 19
| OFM | RBLR | OBLR | CM | VLR | |
| 3-22 (RBLR trap put out) | -- | -- | -- | -- | -- |
| 3-28 | -- | 10* | -- | -- | -- |
| 4-7 (other traps put out) | -- | 0 | -- | -- | -- |
| 4-14 | 0 | 0 | 0 | 0 | 0 |
| 4-21 | 2** | 0 | 0 | 0 | 0 |
| 4-28 | 0 | 0 | 0 | 0 | 0 |
| 5-5 | 1 | 0 | 0 | 0 | 0 |
| 5-12 | 2 | 1 | 0 | 0 | 0 |
| 5-19 | 0 | 0 | 3*** | 1 | 0 |
7. Insecticide Updates for the Southeastern U.S. Vegetable Crop Handbook
There are a
number of new insecticides available for control of vegetable pests that are being
incorporated into the 2009 Handbook. The cyfluthrin insecticide Capture 2E is being
replaced throughout the Handbook with the cyfluthrin brand name Brigade. These pyrethroid
insecticides are in the IRAC group 3.
Capture LFR is a bifenthrin insecticide
formulated for soil insect control. It is applied to soil after mixing directly
with a liquid fertilizer.
There are several new insecticides added for control
of caterpillars. Spinetoram (Radiant SC) is replacing spinosad (Spintor) throughout
the Handbook. Both are IRAC group 5 insecticides. Besides Lepidoptera caterpillars,
Radiant SC is also labeled for used against dipterous leafminers, flower thrips,
Colorado potato beetle, and suppression of pepper weevil.
The rynaxypyr
insecticide Coragen is a suspension concentrate in IRAC group 28. It can be applied
via drip chemigation or as a foliar application. It is labeled for use on Brassica
leafy vegetables, cucurbit vegetables, fruiting vegetables, and leafy vegetables
(non-Brassica). In addition to the various caterpillars on the label, Coragen is
labeled for suppression of silverleaf whitefly nymphs and control or suppression
of Liriomiza species leafminer larvae.
The insecticide flubendiamide
(Synapse) is a 24% WG formulation. It is labeled for control of various caterpillars
on cucurbits, leafy vegetables, Brassica leafy vegetables, leafy vegetables, and
fruiting vegetables. Synapse is in the IRAC group 28.
One trend that
we are seeing is a profusion of new insecticide labels that have two different insecticides
in a pre-mix. Cobalt is a combination of chlorpyrifos and gamma-cyhalothrin. Hero
is a combination of bifenthrin and zeta-cypermethrin while Brigadier is a combination
of bifenthrin and imidacloprid.
The insecticide spirotetramat (Movento)
is an IRAC group 23 insecticide. It is labeled for control of aphids, psyllids,
and whiteflies on fruiting vegetables and tuberous and corm vegetables. Movento
is labeled for use on leafy vegetables and Brassica leafy vegetables for control
of aphids and whiteflies.
The insecticide flonicamid (Beleaf 50 SG) is
in the IRAC group 9C. On vegetables, it is labeled for control of aphids, plant
bugs, and greenhouse whitefly on head and stem Brassica and mustard greens (0 day
PHI), cucurbit vegetables (0 day PHI), fruiting vegetables (0 day PHI), leafy vegetables
(0 day PHI), and potato (7 day PHI).
A new miticide in the IRAC group
10B is etoxazole (Zeal Miticide). It has a federal supplemental label for twospotted
spider mite control on melons. (FH)
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
Soil, Plant and Pest Center
5201 Marchant Drive
Nashville, TN 37211
Copyright 2008 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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