Fruit Pest News
Volume 10, No. 9 June 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. Recent Reports
2. Current Status of Cucurbit Downy Mildew
3. Peach Scab
4. Peach Preharvest Sprays in the Absence of Pristine
5. Switch Fungicide Now Labeled for Cucurbits, Tomatoes, and Root Vegetables
6. Spider Mites, Slugs, and Snails on Strawberries
7. Oriental Fruit Moth on Peach
8. Pheromone Trap Catch Reports
1. Recent Reports
Recent significant reports include: tarnished plant bugs on plasticulture strawberries, potato leafhoppers on apples, first report of peach scab, Phomopsis leaf blight and fruit rot on plasticulture strawberries, and anthracnose on cucumbers. Black rot and anthracnose are active on grapes.
2. Current Status of Cucurbit Downy Mildew
Cucurbit downy mildew was found and confirmed on commercial cucumbers in Franklin County in eastern North Carolina on Friday morning, June 5. See the current distribution of this disease at http://www.ces.ncsu.edu/depts/pp/cucurbit/ . Recent reports have also come from FL and southern GA. However, conditions are not favorable for long-range transport of the spores from the FL and NC sources for the next few days. Nevertheless, keep an eye on the forecasts - http://www.ces.ncsu.edu/depts/pp/cucurbit/forecasts/c090605.php - next week, as the inoculum level is building. Cucumber growers should apply protectant fungicides now, even to very young plants (normally, fungicide sprays aren't initiated until plants begin to run). All cucurbit growers should purchase some downy mildew fungicides to have on hand if needed. Examples are Presidio, Ranman, Tanos, Previcur Flex, and Gavel. (SB)
3. Peach Scab
Peach scab was first seen at Nashville on June 1. Peach scab has a 40-day latent period, which means that symptoms do not appear for 40 days after infection. Control is not needed on varieties that are within 40 days of harvest, since any infections that occur will not have time to develop before harvest. This does not mean that early-maturing varieties will not have scab if it is not showing at this time (a 40-day latent period could be in progress, and could expire before harvest). (SB)
4. Peach Preharvest Sprays in the Absence of Pristine
There is a shortage of Pristine this year. Pristine has very good activity against peach brown rot and is often used in the first preharvest spray, or first two preharvest sprays, for those who make three such sprays. The last spray before harvest would be a sterol inhibitor (SI) such as Elite, Indar, or Orbit. If you cannot obtain Pristine, acceptable alternatives would be Abound or a Topsin M/captan tank mix. If you make three preharvest sprays, it would be preferable to use an SI in the last two sprays. (SB)
5. Switch Fungicide Now Labeled for Cucurbits, Tomatoes, and Root Vegetables
Several new vegetables have been added to the Switch 62.5WG label by Syngenta Crop Protection. Switch can now be used on cucurbit crops for control of Alternaria leaf blight, gummy stem blight, and powdery mildew. On tomatoes, Switch can be used for control of early blight, gray mold, and powdery mildew. On root vegetables such as turnips grown for roots, rutabagas, radishes, and ginseng, Switch can be used for control of Alternaria leaf spots and powdery mildew. It can also continue to be used on turnips grown for greens according to an older registration. The older label listed carrots separately, but they are now included in the root vegetables group.Switch is a combination of two active ingredients - cyprodinil, a systemic component, and fludioxonil, a contact component. The labeled resistance management program consists of two consecutive applications followed by two applications of an unrelated (any FRAC group other than 9 or 12) fungicide. Switch is an effective product against Alternaria, Botrytis, and powdery mildew diseases and will help to give a break to other fungicides in resistance management programs. (SB)
6. Spider Mites, Slugs, and Snails on Strawberries
Wet weather is usually
not thought to be conducive to outbreaks of warm season spider mites such as twospotted
spider mites. Still, there have been reports of spider mites in plasticulture strawberries.
The spider mites live on the underside of the leaves where they are protected from
the driving rains and the elevated planting beds allows for greater heat gain from
the sunlight. Twospotted spider mites can easily go through their lifecycle (egg,
larva, nymph stages, adult, egg again) in two weeks with daytime temperatures in
the mid-80s. Thus, mite populations can increase rapidly when the weather heats up.
Start scouting early and look for stippling (tiny yellow feeding marks) along
the top of the leaf along the midvein. Also, turn over leaves and examine them for
mites, mite eggs and webbing. Miticide applications should be started when mites
populations reach 5 per leaflet. Since most miticides have a one to three day preharvest
interval (PHI), it is best to have mites under control before harvest. Miticides
followed by their (PHI) include Agri-Mek 0.15 EC (3 days), Kelthane 50 WSP (3 days),
Savey 50 WP (3 days), Oberon 2 SC (3 days), Danitol 2.4 EC (2 days), Kanemite 15
SC (1 day), Acramite 50 WP (1 day), Zeal 72 WSP (1 day), Vendex 50 WP (1 day), Brigade
10 WSB (0 days), M-Pede (0 days), and horticultural oils (0 days).
Wet weather
can also lead to snail and slug problems in strawberries. There are only a few products
available for slug and snail control around strawberries and they have relatively
long pre-harvest intervals. Thus, scouting for slugs and snails should start at least
a couple weeks prior to harvest. Inspect plants in the morning when there is still
dew on the plants. Also, look for feeding damage on leaves (trails of dried slime
interspersed with ragged holes). Carbaryl (Sevin 5 Bait) with a PHI of 7 days should
be applied to field edges at dusk. Sevin 5 Bait works best when repeat applications
are made. It will also control various types of soil dwelling insects. Metaldehyde
(Deadline Bullets 4% Bait) has a PHI of 6 days. Band this bait around the edges of
the beds. Care should be taken so that the fruit are not contacted and contaminated
by either the Sevin or the Deadline Bullets Baits. (FH)
7. Oriental Fruit
Moth on Peach
Early-season insecticides applied for plant bugs and plum curculio
usually provide excellent control of Oriental fruit moth (OFM) in Tennessee. A pheromone
trap treatment threshold of 10 moths/trap/week should be used after 3rd cover. In
peach, first generation OFM larvae are primarily found feeding on tender vegetative
growth. The subsequent generations feed inside the fruit.
Imidan is considered
the standard in-season insecticide for plum curculio and OFM since it provides very
good control. Auvant 30 SG is an effective, reduced risk organophosphate replacement.
It is a good choice during thinning. The lower rates of pyrethroids (Asana 0.66
EC, Adjourn 0.66 EC, Bathroid XL 1 EC, Mustang 1.5 EC, Renounce 20 WP, Tombstone
2 EC, Proaxis 0.5 EC, Lambda-T 1 EC, Silencer 1 EC, Taiga Z 1 EC, or Warrior 1 EC)
are effective at Petal Fall when plant bugs are the primary pest species. Now that
plum curculio, lesser peachtree borers, and stink bugs are more abundant, higher
rates of these pyrethroids are needed. (FH)
8. 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 |
| 5-11 | 0 | 0 | 4**** | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
| 5-18 | 5 | 0 | 3 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-21 | 3 | 12 | 23 | 0 | 4 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-26 | 7 | 29 | 10 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 6-1 | 7 | 96 | 38 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 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.
****Biofix for OBLR in Davidson County
was May 11.
Putnam County Pheromone trap Catches for 2009
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 |
| 5-8 | 11 | 0 | 0 | 1 | 0 | 14 |
| 5-15 | 1 | 0 | 0 | 0 | 0 | 15 |
| 5-18 | 3 | 0 | 0 | 1 | 0 | 12 |
| 5-22 | 5 | 14 | 0 | 0 | 0 | 22 |
| 5-25 | 2 | 16 | 3 | 2 | 0 | 1 |
| 5-29 | 0 | 30 | 3 | 1 | 2 | 6 |
*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.
Obion County Pheromone Trap Catches for 2009
| VLR | RBLR | OBLR | CM | |
| 5-1 | 3* | -- | -- | -- |
| 5-12 | 42 | -- | -- | -- |
| 6-1 (Note: missing data [--] prior to June) | 14 | 22 | 2 | 0 |
*Biofix for VLR in Obion County was May 1.
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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