Fruit Pest News
Volume 8, No. 17 July 18, 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.
In This Issue:
1. Supply of PB 1282
2. Phytophthora Blight of Vegetables
3. Small Batch Preparation of Pesticides
4. Phyto Reminder for Quadris/Abound
5. Pesticide Exposure
6. Oriental Fruit Moth
7. Japanese Beetle Numbers Vary By Location
8. Pheromone Trap Catches
1. Supply of Print Copies of PB1282, Commercial Vegetable Disease, Insect and Weed Control
There are still a number of copies of the print version of PB1282, Commercial Vegetable Disease, Insect and Weed Control, available for Tennessee Extension agents to order. Growers, if you don't have a print copy yet and would like one, ask your agent for one. The supply appears to be ample. The electronic version of PB 1282 is available on our web site at http://www.utextension.utk.edu/publications/pbfiles/PB1282.pdf (SB)
2. Vegetables: Phytophthora Blight
A benefit of the dry weather is a reduction in the number of cases of Phytophthora blight (P. capsici) on cucurbit crops. But you can never let your guard down once you have encountered this disease. As they say for black shank disease of tobacco: "Once infested, always infested." That's not a bad policy to follow.
Phytophthora blight is a devastating disease particularly of cucurbit crops and peppers, but also tomatoes, eggplant, snap beans, and lima beans. The destructive nature of the disease and the long life (many years) of an infestation can prevent successful production of susceptible crops for many years. Because of the difficulty of controlling this disease after it occurs, prevention should be emphasized. The action to take when Phytophthora blight is first found in a field depends on the severity of the case. If the blight is widespread throughout a field, attention should be directed to prevention of spread to non-infested fields.
Chemical control of Phytophthora blight in such severe cases is not very effective and not generally recommended. Prevention of spread consists of cultural practices such as cleaning equipment after working in an infested field. Certain disease-control products have activity against P. capsici and may be helpful in light cases of Phytophthora blight. Pre-plant soil applications of mefenoxam can suppress root and crown rot phases of the disease, unless resistance to this fungicide develops. Other products are applied as foliar sprays to protect against airborne spores. The most difficult aspect of this disease to control is the fruit rot phase in crops in which the fruit lies on the ground, such as unsupported vine crops. The potential for disease-control products to be successful is highly dependent on the correction of soil drainage problems. Peppers and cucurbit crops are so susceptible to Phytophthora blight that it is risky to plant these crops in fields in which the disease has ever been known to occur. Some degree of control can be achieved with resistant pepper varieties and hard-rind pumpkin varieties, but cultural practices and chemicals would still be needed.
Be on the lookout for this disease, especially in irrigated fields. Dying plants and rotting fruit are the main symptoms. Be wary of borrowing or lending cultivation equipment, as this organism can be introduced into your field on anything that carries soil particles. (SB)
3. Small-Batch Preparation of Pesticides
When preparing small quantities of a spray mix (e.g. 1 gal.), it is often convenient to use a tablespoon to measure the product. That's fine if the product is a liquid. Any liquid pesticide mixed at 1 pint per 100 gallons of water is always going to be 1 teaspoon per gallon, because both measures are volumes. The problem comes with dry products (wettable powders, dry flowables, water-dispersable granules).
Dry products have different densities, so it is not accurate to convert a weight measure into a volume measure (e.g. tablespoon), unless you know how much that volume weighs. The table below illustrates the range of densities of some common fruit fungicides. You can see the error that would ensue if you assumed, say, that 2 tablespoons per gallon of any dry product was equal to 3 pounds per 100 gallons.
|
Densities of common fruit fungicides. |
||
|
Product |
Grams per level tablespoon |
Approximate no. tablespoons/oz. |
|
basic copper sulfate |
13.0 |
2 |
|
Flint 50DF |
7.1 |
4 |
|
Cabrio 20WDG |
7.0 |
4 |
|
Captan 50WP |
8.8 |
3 1/3 |
|
Carbamate 76WDG |
5.0 |
5 2/3 |
|
Dithane DF |
8.5 |
3 1/3 |
|
Kocide DF |
8.5 |
3 1/3 |
|
Kocide 101 WP |
4.6 |
6 |
|
Manzate 200DF |
10.2 |
3 |
|
Nova 40W |
3.1 |
9 |
|
Pristine 38WDG |
6.0 |
4 2/3 |
|
Switch 62.5WDG |
6.0 |
4 2/3 |
Once you have weighed a level tablespoon of a dry product, you can use that tablespoon to measure the product, because it is then a unit of weight. (SB)
4. Phyto Reminder for Quadris/Abound
With azoxystrobin (Quadris, Abound, Heritage) receiving registrations for so many commodities, its danger to certain apples bears repeating. Azoxystrobin is very phytotoxic to Macintosh and related apple varieties. When spraying strawberries or other crops with an azoxystrobin product, be careful not to allow any drift to nearby apples. Do not even use a sprayer for apples that has ever been used to apply azoxystrobin. Even trace amounts can burn the leaves. Before selling a sprayer that has been used to apply azoxystrobin, clean it out thoroughly, using a tank cleaner. The following varieties have been reported as sensitive to azoxystrobin: Akane, Bromley, Cortland, Cox/Cox's Orange Pippin, Discover, Gala, Grimes, McCoun, Macintosh, Molly's Delicious, Kent, Spartan, Summer Treat, and Summared. Also related to Macintosh are Bancroft, Empire, and Jonamac. Note: Azoxystrobin injury on Gala could be mistaken for Glomerella leaf blotch, to which Gala is also susceptible. (SB)
5. Pesticide Exposure
I was recently contacted about a sad situation in a
third world country where dangerous insecticdes were being applied to vegetables
by workers using backpack sprayers. Most of these insecticides were in the
highest toxicity rating where using backpack sprayers would be extremely
dangerous and against the law. To make matters worse, the workers were hardly
using any of the required personal protective equipment and some of the
insecticides were not even labeled for use on the crop. Besides the danger to
the applicators, the safety of the treated food would probably also be in
question. I would hope that this food would not be shipped here but regardless,
someone will be eating it. While the idea of anything this grievous occurring
here would be hard to believe, it does drive home the point that the pesticide
label is law and safety precautions contained therein are extremely important
and for the safety of all. (FH
6. Oriental Fruit Moth
Oriental fruit moth catches have increased over the
past few weeks. Summer cover sprays on peaches, nectarine and plum should protect
against plum curculio, Oriental fruit moth, plant bugs and stink bugs. While phosmet
(Imidan 70 W) is very effective for these pests, labeled pyrethroid insecticides
can also be used. Moderate pyrethroid rates provide good to excellent control of
Oriental fruit moth, plant bugs, and stink bugs. At the upper rate ranges, pyrethroids
provide good control of plum curculio and suppression of lesser peachtree borer.
While pyrethroids are relatively inexpensive, the main drawback is that their use
tends to promote scale and mite outbreaks. To minimize pyrethroid induced scale
and mite problems, restrict use to early in the season, if possible. If pyrethroids
are used, it will probably be beneficial to use an aggressive dormant season scale
program. (FH)
7. Japanese Beetle Numbers Vary by Location
Japanese beetle
populations had been quickly building in Middle and West Tennessee, especially over
the last several years. This year, numbers are down in many area around Nashville,
although some localized areas have damaging populatons. Illinois has reported record
numbers and I found plenty feeding in soybeans in Jackson last week.
When
Japanese beetles get established in an area, they usually build to peak populations
for several years before eventually moderating. This moderation is thought to be
due to the increasing influence of natural control organisms (predators, parasitoids,
and pathogens). Another important factor can be dry weather which can cause newly
laid eggs to desiccate and possibly can effect larval survival in turfgrass. I can
only speculate on the current situation but it is probably a combination of these
factors. It will be interesting to see if populations remain depressed next year,
especially given the dry soil conditions as we move into the summer egg laying period.
(FH)
8. 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 |
* 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
Phoromone Trap Catches for 2007
| OFM | CM | |
| 3-26 | 1 | 0 |
Putnam County Pheromone Trap Catches for 2007
| 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 Pheromone Trap
Catches for 2007
| 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 |
* 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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