Fruit Pest News
Volume 10, No. 6 May 5, 2009
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 Conditions and First Reports
2. Fruit Crop Actions that are Needed Today (before the next rain)
3. Strawberry Harvest and Rains Don't Mix
4. Grape Black Rot Infection Periods Since April 1
5. Update for Section 18 for Mancozeb on Peppers
6. Grape Insects
7. Pheromone Trap Catches
1. Current Conditions and First Reports
If at all possible, get a fungicide spray on today, as we will back into an extended rainy period tomorrow. We had major infection periods for most diseases during the past few days. See the data for grape black rot in article 4, below. You need to get your prebloom spray on today. Other diseases for which curative fungicides are available should also be treated with those fungicides (article 2, below).
Do I need to re-apply a pesticide spray and how soon? See last week's article.
First reports for the year during the past week: Fusarium crown and root rot of greenhouse tomato, April 27, Blount County; orange rust of blackberry, April 29, Sumner County; black rot of grape, April 30, Davidson County.
2. Fruit Crop Actions that are Needed Today (before the next rain)
Diseases for which control is critical at this time:
Peach scab - Captan and sulfur are the standards. You may wish to consider the use of a strobilurin at this time, because of their wash-off resistance and some curative activity - properties that will be of benefit following the recent infection period and the upcoming rainy period.
Apple scab, cedar-apple rust, and powdery mildew - A sterol-inhibitor would be appropriate for this time. A strobilurin could also be used, but remember that you are only allowed 3 uses per season. Either way, a protectant material should be tank mixed at this time, because other diseases such as sooty blotch and flyspeck are becoming active.
Grape black rot - This is the pre-bloom stage, and black rot control is becoming critical. A major infection period occurred from May 1 - May 4 (see article 4, below). Use a sterol inhibitor and tank mix with a protectant for control of other diseases.
Strawberries - See article below. (SB)
3. Strawberry Harvest and Rains Don't Mix
The monsoon weather of May 1 through May 4 coincided with early strawberry harvest for many Tennesseans. Expect some berry rots. I have not heard of any anthracnose infestations this year, so hopefully you will not have to deal with that berry rotter. Botrytis is always available, so as soon as the ground is firm enough to support the equipment, apply a Botrytis material such as Switch, Elevate, or Scala (0, 0, and 1-day PHI's, respectively). Since none of these materials can be applied consecutively, purchase two of them and alternate them. Captan (1-day PHI) is also a good Botrytis material and can be alternated or tank mixed with the other materials.
Much of the rotting you will see in excessively wet conditions is not controllable with fungicides, as it is caused by soft-rotting bacteria. The berries become engorged with water, and bacteria move in and rot them. There is no control for this. Hopefully, matted row plantings are well mulched so that berries have drainage and are not resting on wet soil. (SB)
4. Grape Black Rot Infection Periods Since April 1
Infection periods since April 1 are presented below. The weather data upon which this information is based was collected on a Spectrum WatchDog system placed in Nashville, TN. This information may familiarize you with this method of timing the application of fungicides in an effort to improve control while reducing the number of sprays. Each disease is based on a different "model," or system of predicting infection. Both models are based on the length of time the leaves stay wet at each temperature. They can be used to apply curative fungicides after infections occur or, by entering weather forecasts, to time fungicide applications for best effect. (SB)
|
Date, 2009 |
High temp |
Low temp |
Wet hours* |
Risk level |
|
Apr 19 |
63 |
53 |
19.0 |
1.72 |
|
Apr 20 |
69 |
49 |
7.0 |
2.07 |
|
May 1 |
75 |
59 |
22.0 |
2.80 |
|
May 2 |
65 |
59 |
12.5 |
4.19 |
|
May 3 |
63 |
58 |
21.0 |
2.28 |
|
May 4 |
70 |
55 |
17.5 |
3.83 |
*Hours above a threshold level of wetness.
5. Update on Section 18 for Mancozeb on Peppers
The effort to request a Section 18 for mancozeb on peppers is experiencing a delay, but hopes are still intact for a label. The discontinuation of maneb fungicide has created a need for a replacement material that will enhance the bacteria-controlling property of copper. Early indications of an expected smooth sailing through EPA have changed. Data used in a Section 3 (national) label petition for mancozeb on peppers was thought to be adequate for the Section 18 requests planned by the states. However, the Section 3 label also is being slowed, and may not be approved by the July 31 target date.
Tennessee is one of several states that are interested in a Section 18 label for mancozeb on peppers. The plan is for one state to submit a request for a Section 18, and other states will ask for "Me too" labels by using the first state's proposal as a template and modifying it to fit their situations. Kentucky will be the first state to submit the request. We will keep you posted on the progress of the requests.
If pepper growers have any maneb or can locate any, they should use it. The label is still valid; availability of the product is the problem. (SB)
6. Grape Insects
Be on the lookout for spring pests of grapes such as aphids, leafhoppers,
and flea beetles. While inspecting, also look for predatory insects and parasitoids.
Aphids are an example of a pest that can often be controlled naturally by predaceous
insects and parasitoids. While the general recommendation is to treat for aphids
if they become abundant and the terminals or foliage are becoming deformed, chemical
control may not be needed in some circumstances. If insecticide has not been used
within the last week or two and natural predators such as lady beetles and syrphid
flies are abundant, then chemical control may not be needed. These predaceous insects
can often control aphid populations naturally within two weeks.
Low levels
of leafhoppers probably do not warrant control. Inspect plants and if plant injury
is evident (weak, unthrifty growth) or if 10 leafhopper nymphs or adults are found
per leaf, chemical control is needed.
Flea beetles chew small holes in the
leaves. Chemical control will be needed if more than 10% foliar injury is found
and flea beetle adults are abundant.
The upcoming post-bloom (summer cover)
sprays will address major direct pests such as grape berry moth, grape curculio,
green June beetle, Japanese beetle, wasps, and yellowjackets. Since grape berry moths
have already been detected in pheromone traps and they lay there eggs on the berry
clusters, inspect and treat if infested clusters are found or if you have a history
of damage from this pest. (FH)
7. Pheromone Trap Catches and Biofixes (FH)
Nashville
(Davidson County) Pheromone Trap Catches for 2009
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), beet armyworm (BAW), squash vine borer (SVB), fall armyworm (FAW)
| OFM | RBLR | OBLR | CM | GBM | VLR | BCW | DBM | AW | CL | BAW | SVB | FAW | |
|
3-13 (Put out RBLR trap) |
-- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-20 | -- | 29* | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| 3-23 | -- | 14 | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
|
3-30 (put out BCW trap) |
-- | 9 | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
|
3-31 (put out OFM, CM, VLR, OBLR traps) |
-- | 10 | -- | -- | -- | -- | 0 | -- | -- | -- | -- | -- | -- |
| 4-2 | 4** | 2 | 0 | 0 | -- | 0 | 0 | -- | -- | -- | -- | -- | -- |
|
4-3 (put out AW trap) |
-- | -- | -- | -- | |||||||||
|
4-8 (put out GBM, DBM, BAW, FAW, SVB, CL traps) |
12 | 19 | 0 | 0 | -- | 0 | 2 | -- | 4 | -- | -- | -- | -- |
| 4-13 | 9 | 17 | 0 | 0 | 4*** | 0 | 0 | 0 | 7 | 0 | 0 | 0 | 0 |
| 4-20 | 4 | 7 | 0 | 0 | 5 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-27 | 6 | 0 | 0 | 0 | 16 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-4 | 2 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 |
* Biofix for RBLR in Davidson County estimated as prior to March 20 (trap not
out early enough).
**Biofix for OFM in Davidson County was April 2.
***Biofix
for GBM in Davidson County was April 13.
Putnam County Pheromone trap Catches for 2008
Tufted Apple Bud Moth (TABM)
| OFM | RBLR | OBLR | CM | VLR | TABM | |
| 3-16 | -- | 10* | -- | -- | 0 | -- |
| 3-18 | -- | 31 | -- | -- | 0 | -- |
| 3-20 | -- | 2 | -- | -- | 0 | -- |
| 3-23 | -- | 2 | -- | -- | 0 | -- |
| 3-25 | -- | 0 | -- | -- | 0 | -- |
| 3-27 | -- | 6 | -- | -- | 0 | -- |
| 3-30 | -- | 11 | -- | -- | 0 | -- |
|
4-1 (put out OBLR, TABM traps) |
||||||
| 4-3 | -- | 10 | 0 | -- | 0 | 0 |
|
4-10 (put out OFM trap) |
-- | 11 | 0 | -- | 0 | 0 |
| 4-13 | 4 | 3 | 0 | -- | 0 | 0 |
|
4-17 (put out CM trap) |
12 | 9 | 0 | -- | 0 | 0 |
| 4-20 | 10 | 0 | 0 | 2** | 0 | 0 |
| 4-22 | 4 | 0 | 0 | 0 | 0 | 1 |
| 4-24 | 7 | 2 | 0 | 2 | 0 | 2*** |
| 4-27 | 4 | 0 | 0 | 1 | 0 | 0 |
| 5-1 | 5 | 0 | 0 | 0 | 0 | 0 |
*Biofix for RBLR in Putnam County estimated as prior to March 16 (trap not out
early enough).
**Biofix for CM in Putnam County was April 20.
.**Biofix for
TABM in Putnam County was April 24.
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 2009 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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