Fruit Pest News
Volume 6, No. 8 May 10, 2005
A weekly, online newsletter whose goal is to update Extension agents and growers of commercial tree fruit and small fruit crops
on diseases and insects 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. Observations
2. Apple: Fire Blight, Secondary Blooms
3. Small Batch Preparation of Pesticides
4. Apple: Phyto Reminder for Quadris/Abound
5. Tree Fruit: San Jose Scale
6. Grape Berry Moth
7. Pheromone Trap Catches
1. Observations
Until the current warm weather occurred, temperatures remained consistently cool, and we remain a good week behind normal in plant development and the first appearance of disease symptoms. First reports for the year during the past week: anthracnose of strawberry (fruit and stem) -- May 4, Bledsoe County; bacterial speck of tomato -- May 4, Williamson County; powdery mildew of apple -- May 10, Davidson County. Watch for powdery mildew on susceptible apple varieties. Here at the Diagnostic Center, we have been seeing lots of climbing cutworm damage on young grapes, but cedar-apple rust of apple appears to be lighter than normal. (SB)
2. Fire Blight: Secondary Blooms
Most apple varieties have finished blooming, with the exception of secondary (tag-on) blooms. The MaryBlyt program ceases to predict fire blight infection periods and the need for streptomycin sprays after all blooms are gone. We do not recommend the use of streptomycin after bloom because of its ineffectiveness against shoot blight infections, and because such use increases the risk of resistance developing. The time to prevent shoot blight is during bloom (with streptomycin applications) and during the dormant period (by pruning out cankers).
Beware, however, of tag-on blooms. Streptomycin sprays may be needed as long as they are present. Loosing a few late blossom clusters to fire blight may not seem important, but the bacteria produced by just a few infected blossoms can result in a significant shoot blight epidemic. In such warm weather, tag-on blooms can easily become infected and negate all your hard work in preventing infections during the bloom period! If only a few secondary blooms are present, it would be worth your while to remove them by hand, because they potentially represent the beginning of a fire blight epidemic! (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 Janamac. Note: Azoxystrobin injury on Gala could be mistaken for Glomerella leaf blotch, to which Gala is also susceptible. (SB)
5. San Jose Scale
San Jose scale can be a serious pest of tree fruit. Their
feeding can stress and weaken trees while the movement of crawlers onto the fruit
can significantly lower the value of the fruit. Since I did not put out a pheromone
trap for the flying adult males, I will refer to the University of Arkansas Department
of Entomology Fruit Pest Management web site at http://comp.uark.edu/~dtjohnso/scout05.html
Click on 2005 Fruit Pest Pest Degree-Days to get a list of predicted emergence
dates for various fruit pests including San Jose scale. The three sites monitored
in Arkansas predict scale crawler emergence approximately between May 4 and May 22.
Tennessee growers should also be looking for crawlers during this general time period.
A sticky trap for scale crawlers can be made on infested twigs by using sticky
double-sided Scotch tape wrapped around the twig or a wrap of black electrical tape
with a thin layer of petroleum jelly on it. The detection of the crawlers will allow
you to better time your insecticide applications. (FH)
6. Grape Berry Moth
The
University of Arkansas uses a 47.14 degree F base temperature when calculating Degree-Days.
The biofix in Arkansas was April 10 while our biofix at the Ellington Center in
Nashville was April 7. The predicted hatch period for the three trap sites in Arkansas
was April 27 through May 29. Start inspecting grapes now for the first signs of
feeding on flower buds, blooming flowers and later the small fruit. (FH)
7. Pheromone Trap Catches
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)
| Date | OFM | RBLR | OBLR | CM | GBM | VLR | BCW |
| 3-11 (put out RBLR trap) | -- | 0 | -- | -- | -- | -- | -- |
| 3-14 | -- | 16* | -- | -- | -- | -- | -- |
| 3-18 (put out OFM, OBLR,CM, VLR traps) | -- | 1 | -- | -- | -- | 0 | -- |
| 3-21 | 0 | 17 | 0 | 0 | -- | 0 | -- |
| 3-24 | 0 | 19 | 0 | 0 | -- | 0 | -- |
| 3-29 | 0 | 23 | 0 | 0 | -- | 0 | -- |
| 3-30 (put out GBM & BCW traps) | 0 | 10 | 0 | 0 | 0 | -- | |
| 4-4 | 1 | 34 | 0 | 0 | 4** | 0 | 0 |
| 4-7 | 1 | 12 | 0 | 0 | 2 | 0 | 0 |
| 4-12 | 5**** | 12 | 0 | 0 | 10 | 0 | 2*** |
| 4-14 | 2 | 1 | 0 | 0 | 5 | 0 | 0 |
| 4-18 | 11 | 5 | 0 | 0 | 5 | 0 | 0 |
| 4-20 | 9 | 1 | 0 | 0 | 2 | 0 | 0 |
| 4-22 | 4 | 0 | 0 | 0 | 4 | 0 | 0 |
| 4-25 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 4-29 | 0 | 0 | 0 | 0 | 1 | 0 | 0 |
| 5-2 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-6 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| 5-9 | 10 | 0 | 0 | 0 | 2 | 0 | 0 |
* Biofix for RBLR in Davidson County estimated as occurring on March 12.
**Biofix
for GBM in Davidson County is April 4.
***Biofix of BCW in Davidson County on
April 12.
****Biofix for OFM in Davidson County on April 12.
Bradley County
| Date | OFM | RBLR | CM |
| 3-10 (put out two RBLR traps) | -- | -- | -- |
| 3-12 | -- | 2* | -- |
| 3-21 | -- | 45 | -- |
| 3-23 (put out four OFM traps) | -- | -- | -- |
| 3-25 | 28** | -- | 0 |
| 3-28 | 18 | 41 | 0 |
| 4-4 | 67 | 12 | 0 |
| 4-11 | 43 | 8 | 0 |
| 4-15 | -- | -- | 1 |
| 4-16 | -- | -- | 4*** |
| 4-18 | 21 | 2 | 2 |
*Biofix for RBLR in Bradley County on March 12.
**Biofix for OFM in Bradley
County on March 25.
***Biofix for CM in Bradley County on April 16.
Putnam
County
| Date | OFM | RBLR | OBLR | CM | VLR |
| 3-21 | 0 | 52* | 0 | 0 | 0 |
| 3-23 | 0 | 10 | 0 | 0 | 0 |
| 3-25 | 0 | 12 | 0 | 0 | 0 |
| 3-28 | 0 | 20 | 0 | 0 | 0 |
| 3-30 | 0 | 0 | 0 | 0 | 0 |
| 4-1 | 0 | 5 | 0 | 0 | 0 |
| 4-4 | 0 | 5 | 0 | 0 | 0 |
| 4-6 | 3** | 7 | 0 | 0 | 0 |
| 4-8 | 0 | 1 | 0 | 0 | 0 |
| 4-18 | 6 | 7 | 0 | 0 | 0 |
| 4-22 | 2 | 3 | 0 | 0 | 0 |
| 4-25 | 0 | 4 | 0 | 0 | 0 |
| 4-27 | 2 | 0 | 0 | 0 | 0 |
| 4-29 | 0 | 0 | 0 | 0 | 0 |
| 5-2 | 0 | 0 | 0 | 0 | 0 |
*Biofix for RBLR in Putnam County on March 21.
**Biofix for OFM in Putnam County
on April 6.
Obion County
| Date | OFM | RBLR | OBLR | CM | VLR |
| 3-25(put out traps) | -- | -- | -- | -- | -- |
| 3-28 | 0 | 0 | 0 | 0 | 0 |
| 4-4 | 1 | 9* | 3** | 8*** | 0 |
| 4-11 | 3**** | 0 | 0 | 0 | 0 |
| 4-18 | 0 | 0 | 7 | 0 | 0 |
| 4-25 | 2 | 0 | 0 | 0 | 1***** |
| 5-3 | 1 | 0 | 0 | 0 | 6 |
| 5-9 | 5 | 0 | 0 | 0 | 4 |
*Biofix for RBLR in Obion County estimated to be on March 12 (trap not out early
enough).
**Biofix for OBLR in Obion County on April 4 (waiting for confirmation).
***Biofix
for CM in Obion County on April 4 (waiting for confirmation).
****Biofix for OFM
in Obion County on April 11.
*****Biofix for VLR in Obion County on April 25 (waiting
for confirmation).
Other Pheromone Trap Catches for Davidson County in 2005
Diamondback Moth (DBM), American Plum Borer (APB), Cabbage Looper (CL), Armyworm
(AW)
| Date | DBM | APB | CL | AW |
|
4-18 (put out traps) |
-- | -- | -- | -- |
| 4-20 | 5* | 3** | 0 | 0 |
| 4-22 | 3 | 3 | 0 | 0 |
| 4-29 | 6 | 0 | 3*** | 0 |
| 5-2 | 41 | 2 | 4 | 6**** |
| 5-4 | 23 | 0 | 0 | 0 |
| 5-6 | 27 | 0 | 0 | 0 |
| 5-9 | 106 | 1 | 0 | 0 |
* Biofix of DBM in Davidson County probably earlier than April 20
**Biofix
of APB in Davidson County probably earlier than April 20
***Biofix of CL in Davidson
County on April 29
****Biofix of AW in Davidson County on May 2
Knox County
*
| Date | OFM | RBLR | OBLR | CM | VLR | TABM |
| 5-2 (traps put out 4-18) | 20 | 0 | 3 | 3 | 2 | 17 |
*The Knox County traps were put out by a first time cooperator still learning to identify. the moths. Correspondingly, the trap counts for May 2 remain suspect. We do know that the traps were put out too late to accurately determine a biofix for Oriental fruit moth (OFM) and redbanded leafroller (RBLR). The obliquebanded leafroller (OBLR), codling moth (CM), variegated leafroller (VLR) and tufted apple budmoth (TABM) catches are possible biofixes or at least early in their moth flights.
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 2005 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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