Fruit Pest News
Volume 8, No. 18 July 25, 2007
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.
Editor's Note: Fruit Pest News will be published every other week for the remainder of the 2007 growing season. The next issue will be August 9.
In This Issue:
1. Cucurbit Powdery Mildew Reminder
2. Bacterial Spot of Tomato
3. Ozone Injury in Vegetables
4. Bitter Rot of Grapes
5. Japanese Beetles and Green June Beetles on Small Fruit
6. Grape Root Borer
7. Pheromone Trap Catches
1. Cucurbit Powdery Mildew Reminder
As powdery mildew season gets cranked up, remember that we no longer recommend the strobilurins (Quadris, Flint, Cabrio, Pristine) for control of this disease because of the prevalence of resistant strains and the resulting poor control. Use Nova, Procure, or sulfur in a tank mix with a basic fungicide such as mancozeb or chlorothalonil, preferably the latter during powdery mildew season. But watch for slippage with Nova and Procure, because this class of fungicides also is showing signs of resistance problems with powdery mildew. For further information on this topic, see the May 22 issue of Fruit Pest News, and for information on cucurbit spray programs, see the June 19 issue. (SB)
2. Bacterial spot of tomato
We are seeing a lot of bacterial spot of tomato and pepper. Home gardeners, be careful about mistaking bacterial spot for Septoria leaf spot. Leaf spots caused by Septoria are about the size of a pin head and slightly larger, while those caused by bacteria are smaller. Flip the leaf over. If the lesions are easier to see on the bottom side of the leaf than the top, it's probably bacterial. Both diseases cause the leaves to turn yellow, then brown. Bacterial spot sometimes involves fruit lesions, but not always. Fruit lesions are brown, scabby and up to 1/8 inch in diameter.
The fungicides used for Septoria leaf spot and early blight won't work for bacterial spot, because it's caused by a bacterium rather than a fungus. A fixed copper spray is needed for control of bacterial spot. Bacterial control is enhanced by mixing maneb or mancozeb with the copper, and you get fungal disease control to boot (although copper provides some fungal control). However, maneb and mancozeb have 5-day waiting periods before harvest. Since you will probably pick more often than that, you shouldn't use these materials after harvest begins. A chlorothalonil fungicide can be used at that time.
Commercial growers can also use Actigard, the plant resistance activator, but this program should be begun before the disease begins.
Organic growers can use copper or Serenade for bacterial spot control. (SB)
3. Ozone Injury in Vegetables
Atmospheric ozone levels have been high lately, with television stations issuing alerts to sensitive people on some days. The same ozone can be harmful to some plants. The exposure of sensitive plants for 4 hours at levels of 0.04 to under 1.0 ppm of ozone will produce injury. Ozone is produced naturally in the upper atmosphere and by man, from the byproducts of the combustion of coal or petroleum fuels, as in internal combustion engines.
Sensitive vegetable crops include snap beans, carrots, sweet corn, gourds, cantaloupes, green peas, potatoes, pumpkins, squash, tomatoes, turnips, and watermelons. Among fruit crops, grapes, peaches, and strawberries are sensitive. Cucumbers and peppers are considered resistant.
Symptoms can range from pale leaf color to bleached and the upper leaf surface may be stippled or flecked, especially on the highly-exposed areas of the leaf. Plant health is affected by the loss of photosynthetic area. Rapidly-growing plants are affected more than mature plants, and irrigated plants can be expected to show more symptoms than drought-stressed plants. In cucurbit crops that have covered the ground, ozone injury appears as pale-colored strips through the field, with the pale strips being the older, crown leaves of the row. The damage may later affect the younger leaves. (SB)
4. Bitter Rot of Grape
If
you are seeing a rot of mature berries (8% sugar or above), the culprit is probably
bitter rot. Black rot, which has a similar appearance, occurs in green berries. Bitter
rot can be a particular problem to wine grapes because of the unpleasant flavor it
can impart to the wine. Catawba is particularly susceptible.
The causal fungus
usually invades a berry from the pedicel (berry stem). As
the berry rots, concentric rings of fungal fruiting bodies appear. Within a couple
of days, the berry softens and is easily detached. Berries that do not fall off continue
to dry and become firmly attached. When shriveled, the berries look much like berries
affected by black rot or other fruit rots.
The bitter rot fungus overwinters
on fallen leaves and berries and in the bark of year-old canes. The disease cycle
on fruit starts shortly after flowering, when the fungus invades the natural warts
on the berry stems and remains latent until the berry reaches maturity. It then invades
the stem and moves into the berry, where a rot forms and spores are produced on the
surface. Spores that are splashed to injured fruit cause new infections.
Generally,
broad-spectrum fungicides such as captan, ferbam, mancozeb (77-day PHI) and
the strobilurins (Flint, Abound, Pristine, Sovran) are effective
in controlling bitter rot. Used around bloom time and afterward, these materials
help prevent pedicel infections. Late season sprays are needed to prevent secondary
infections. (SB)
5. Japanese Beetles and Green June Beetles on Small Fruit
Both the Japanese
beetle and the much larger green June beetle can be significant fruit pests, especially
around harvest. The Japanese beetle can also be a major defoliator. This year in
many locations, the Japanese beetle populations are low while the green June beetle
populations have tended to be more troublesome. The pre-harvest interval needs to
be considered, especially when using an insecticide near harvest time. One of the
best insecticides used for Japanese beetle and green June beetle control is carbaryl
(Sevin 80 WSP). The problem with using Sevin on small fruit is that its pre-harvest
interval (PHI) is 7 days (it has to be used at least 7 days prior to harvest). It
is thus beneficial to apply Sevin a week prior to harvest when beetle activity is
seen.
What can be used closer to harvest or during harvest? In brambles,
bifenthrin (Capture 2E, Brigade 10 WSB) has a 3 day PHI, malathion 57 EC has a 1
day PHI, pyrethrins plus rotenone (Pyrellin EC.) has a 12 hour PHI, and azadiractin
(Aza-Direct) has a zero day PHI.
In bunch grapes, Malathion 57 EC has a 3
day PHI and Pyrellin E.C.has a 12 hour PHI. In blueberries, imidacloprid (Provado
1.6F) has a 3 day PHI, Malathion 57 EC has a 1 day PHI, Pyrellin EC. has a 12 hour
PHI, and Aza-Direct has a zero day PHI. (FH)
6. Grape Root Borer
The
grape root borer is a very damaging clearwinged borer pest of grape vines. Whether
you have a crop of grape this year or not, vines need to be protected from grape
root borers. Lorsban 4E at 4-5 pints/acre, is applied to the soil as a dilute mixture
so that 2 quarts of the mixture is applied per vine. The spray should not contact
the fruit or foliage using flood nozzles and low pressure (40-60 psi). When timing
this application, it is important to consider the PHI, which is 35 days. If there
is no fruit to harvest, apply the Lorsban 4E in mid-July, after the first moths
are caught in your pheromone traps. If there is fruit on the vines and the PHI does
not allow you to treat before harvest, treat immediately after harvest. The adult
grape root borers can be monitored using pheromone traps. Most years, the adults
start to emerge in early July and can continue to emerge into early September for
about a 2 month flight period.
A nonchemical control of grape root borer
is to use clean cultivation and mounding of soil around the base of the vine on August
1 or to use plastic mulch extending 3 feet out from the base of vines. (FH)
7. 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 |
| 6-4 | 7 | 1 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| 6-11 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
| 6-19 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 6-26 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 7-2 | 0+ | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 7-9 | 2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 |
| 7-17 | 23 | 9 | 0 | 0 | 0 | 0 | 0 | 0 | 4 | 0 |
| 7-23 | 25 | 9 | 1 | 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.
+ Pheromone lure missing
Bradley County
| OFM | CM | |
| 3-26 | 1 | 0 |
Putnam County
| 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 |
| 5-28 | 0 | 15 | 0 | 2 | 0 |
| 6-2 | 0 | 26 | 0 | 0 | 0 |
| 6-4 | 0 | 8 | 0 | 0 | 0 |
| 6-8 | 0 | 0 | 0 | 0 | 0 |
| 6-13 | 3 | 11 | 0 | 0 | 0 |
| 6-15 | 4 | 0 | 0 | 0 | 0 |
| 6-20 | 13 | 25 | 0 | 0 | 0 |
| 6-22 | 5 | 0 | 0 | 0 | 0 |
| 6-25 | 5 | 0 | 0 | 0 | 0 |
| 6-27 | 2 | 3 | 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 |
| 6-4 | 2 | 7 | 1 | 0 | 2 |
| 6-11 | 10 | 2 | 0 | 0 | 0 |
| 6-20 | 6 | 0 | 2 | 0 | 3 |
| 6-25 | 2 | 0 | 0 | 0 | 0 |
| 7-2 | 3 | 0 | 0 | 0 | 6 |
| 7-12 | 10 | 0 | 0 | 0 | 3 |
| 7-16 | 3 | 0 | 0 | 0 | 0 |
| 7-23 | 12 | 0 | 0 | 0 | 3 |
* 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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