Fruit Pest News
Volume 9, No. 13 June 25, 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. The New Ridomil Gold Label
2. Cucurbit Downy Mildew Situation
3. Cucurbit Crops: Spray Program for Disease Control
4. Japanese Beetles and Green June Beetles
5. Oriental Fruit Moth and Codling Moth
6. Corn Earworm and European Corn Borer
7. Pheromone Trap Catches
1. The New Ridomil Gold Label
Ridomil Gold EC has been replaced with a water based formulation, Ridomil Gold SL. The label for the SL formulation is more flexible in that it allows the use of the product after planting even if none was used prior to planting. You can wait until after planting to apply it, but don’t wait too long – Ridomil needs to be in the roots before infection, for best control.
The SL label is organized differently from the old EC label. All crops are listed in each of two parts. Part 1 is for preplant applications and Part 2 is for postplant applications. In Part 2, no preplant applications are required and postplant use is described.
Ridomil greatly benefits from soil incorporation. Vegetable and fruit operations that apply Ridomil through irrigation don't have to worry about incorporation since the water carries the chemical to the root zone. If you apply Ridomil with a sprayer, position the nozzles so the spray is deposited under the plants (don't try this on plastic-mulched crops) and covered with soil by the cultivator. Newly-planted crops may not need cultivation, but if rainfall does not occur within 24 hours, you must incorporate the Ridomil with cultivation or sprinkler irrigation. (SB)
2. Cucurbit Downy Mildew Situation
Cucurbit downy mildew has been found this growing season in several counties in Florida, southern Georgia, and one in eastern Texas, western Louisiana, near Charleston S.C., and southern Ontario, Canada. These reports are being used as the basis of downy mildew predictions made by the North American Disease Forecasting Center, http://www.ces.ncsu.edu/depts/pp/cucurbit . The success of this system depends on knowing where the spores are, and we depend on you to let us know if downy mildew occurs on your farm. This disease can be very serious on cucurbit crops. It needs moisture to proliferate, but is not inhibited by high temperatures, as most downy mildews are.
As a testament to the seriousness of cucurbit downy mildew, sentinel plots have been established in most eastern states, to aid in monitoring its distribution and in preparing for its occurrence. These plots include seven types of cucurbits and are monitored each week for evidence of downy mildew. We have plots at Jackson and Springfield in TN.
Please let us know if you see what you suspect is downy mildew. (SB)
3. Spray Program for Disease Control in Cucurbit Crops
Your strategy for spraying your cucurbit crop (watermelons, pumpkins, etc.) for disease prevention depends on the stage of growth of the crop. Elaborate spray programs are seldom needed on young crops. Following is the spray program I recommend:
Early season:
Use a primary fungicide (chlorothalonil, mancozeb, or maneb) every 7 to 14 days (more frequently in wet weather, less frequently in dry weather). Begin the program at vine tip-over to early bloom (3 to 4 weeks after seeding). Inspect the field for disease symptoms beginning at seedling emergence so that the spray program can be started sooner than planned, if needed. Also, look for insects regularly. If microdochium blight appears in pumpkin or squash, Flint or Cabrio should be alternated with the primary fungicide. Otherwise, there is little need to rotate the primary fungicides with other fungicides in the early season. (Chlorothalonil, mancozeb, and maneb are not subject to the development of resistance, so continued use is not a problem).
Mid-Late Season:
Scout for powdery mildew when this disease becomes a threat, around mid-summer. When the first powdery mildew colonies (circular, white patches) are seen, add sulfur, Nova, or Procure to the tank with the primary fungicide (preferably chlorothalonil, when powdery mildew is present). Quintec can be used on melons. It is no longer recommended that the strobilurin fungicides (Flint, Quadris, Cabrio, Pristine) be used for powdery mildew control, because of resistance problems. Various diseases can occur in mid-late season, and the choice of fungicides should be determined by what diseases appear in the current year, or have occurred in the field in previous years. For example, Revus or Ranman should be included if Phytophthora blight is in the picture. Add a fixed copper to the tank mix if angular leaf spot or bacterial leaf spot appear. The relative effectiveness of the labeled fungicides can be found in UT's Commercial Vegetable Disease Control Guide . Air blast sprayers are needed when canopies become thick. Apply sprays every 7 to 14 days, depending on rainfall. (SB)
4. Japanese Beetles and Green June Beetles
The exceptionally dry soil conditions
across the state last summer appear to have a silver lining. Turfgrass white grub
survival was very low except where turfgrass was irrigated. Thus, few adult Japanese
beetles have emerged and it looks like even lower populations of green June beetles
could be the norm for this summer. Now, if only we had less feeding pressure from
birds. (FH)
5. Oriental Fruit Moth and Codling Moth
We continue to catch
very low numbers of Oriental fruit moths and codling moths in pheromone traps this
year. It appears that the lack of wild and cultivated fruit last year has led to
the very low populations so far in 2008. (FH)
6. Corn Earworm and European Corn
Borer
When growing sweet corn, it is advantageous to monitor for corn earworm
(CEW) and European corn borer (ECB) moths using the metal funnel type Hartstack pheromone
traps for CEW and either blacklight traps or pheromone traps for ECB. These lepidopteran
pests have several generations during the summer and the populations tend to increase
with each subsequent generation. Thus, there is usually less pest pressure in the
earliest maturing sweet corn crops. The use of traps may allow growers to delay
the onset of insecticidal sprays or to skip some sprays. Growers should be able
to eliminate some insecticide sprays when CEW and ECB moths are not active and laying
eggs. Also, trap catches can alert growers to when pest pressure should be high
and increased insecticide use is warranted. This will hopefully allow growers to
produce a higher quality crop. (FH)
7. 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 |
* 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 |
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 |
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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