Fruit Pest News
Volume 7, No. 7 April 26, 2006
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. Current Conditions
2. Blackberries: Watch for Orange Rust
3. Grape: Critical Period for Black Rot Control
4. Apple: First Fire Blight
5. Beans: Is Soybean Rust a Concern?
6. Brambles: Capture 2EC for Raspberry Crown Borer
7. Pheromone Trap Catches and Biofixes
1. Current Conditions
The weather remains somewhat dry, despite some shower activity. Tomato growers, see last week's issue for information on how this impacts tomato spotted wilt virus. First reports for this week: Black rot of grape, April 22, Williamson County; fire blight of apple, April 22, Bradley and Williamson Counties; cedar-apple rust, April 22, Williamson County. (SB)
2. Watch for Orange Rust in Blackberries
Orange rust can be very
destructive to blackberries and black raspberries. Most of the blackberry varieties
that we grow in Tennessee are moderately to highly resistant to orange rust. However,
some varieties, such as Navaho, are quite susceptible.
The fungus causes
plants to be so stunted and weakened that they produce little or no fruit. The fungus
is systemic in the plant, and is perennial inside the below-ground parts. Once a
plant is systemically infected by orange rust, it is infected for life. It is
for this reason that removal of infected plants is recommended, to prevent spread
of the fungus to other plants.
The
time to control orange rust is in the spring. Your queue to take action is the appearance
of weak, spindly new shoots with pale green to yellowish leaves. Such plants should
be removed before they begin to produce the orange-colored, blister-like pustules
on the lower leaf surface. The orange pustules contain spores that spread to other
plants and cause new infections that may not become apparent until the following
spring.
The fungicides Nova, Pristine, and Cabrio can be used for control of orange rust. These fungicides help prevent leaf infections. They will not cure a systemically-infected plant. Begin applications soon (the orange pustules should mature and release their spores sometime in the month of May) and continue every 10 to 14 days until mid-summer. For Nova, the maximum amount is 10 oz per acre per year, and the rate per application is 1.25 to 2.5 oz per acre. Cabrio is labeled at 11 - 14 oz per acre, Pristine at 18 - 23.5 oz per acre, and the sum of the number of applications for these two materials cannot exceed four. (SB)
3. Grape: Critical Period for Black Rot Control
Grapes are at the pre-bloom stage of growth. This is the most critical period for control of black rot disease. Leaf symptoms have already appeared. If black rot can be controlled during the immediate pre-bloom, bloom, and immediate post-bloom stages of growth, successful control should be possible throughout the season. Be sure you don't miss this fungicide spray! (SB)
4. First Fire Blight
The first report of fire blight comes from Bradley and Williamson Counties, on April 22. Look for wilting of shoots or side spurs associated with blossoms, where the bacteria enter. Most apple cultivars are now at petal fall and are no longer subject to blossom infections, unless tag-on blooms remain. (SB)
5. Is Soybean Rust a Concern on Horticultural Beans?
When soybean rust (SBR) arrived in the United States, the horticultural bean industry understandably was concerned that the disease might pose a threat to these crops, including snap bean, lima bean, kidney bean, southern pea, and English pea.. All are hosts of SBR, as are 87 other species of legumes. In general, SBR is considered a minor problem on horticultural beans, although most information has been obtained with artificial inoculations in greenhouses. SBR has not proven to be a problem on horticultural beans in Brazil.
While experimental evidence is lacking, the general consensus is that members of the genus Phaseolus, as a whole, are much less susceptible to SBR than soybeans. Phaseolus includes most of the types of horticultural beans that Tennesseans are likely to grow other than peas (Pisum) and southern peas (Vigna). M.R. Miles, of USDA-ARS, reports that “it is difficult to find SBR in fields of Phaseolus in South Africa, even when the adjacent soybeans are heavily infected.”
However, strains of the rust fungus can vary in virulence, and cultivars of the crops can vary in susceptibility. At the University of Florida experiment station at Quincy, a kidney bean cultivar had twice the level of infection as another kidney bean cultivar in a field trial last year in which SBR occurred naturally. The kidney beans and a scarlet runner bean line had noticeable SBR infection, although the severity was not as great as that in an adjacent soybean field. A lima bean line was much more resistant than the kidney beans or runner bean. The point here is that cultivars of a crop can differ in susceptibility.
We should keep an eye on SBR happenings in Florida, since their growing season is ahead of ours, and the behavior of SBR on horticultural beans there can be instructive to us.
If it appears that some types of beans may benefit from chemical protection, there are several registered fungicides that are effective against rusts. Protectant products include the strobilurins (Quadris, Headline), Endura, chlorothalonil, and sulfur. On snap beans, Nova can also be used. Nova is a sterol inhibitor, and provides kick-back activity, useful if infections have already occurred when the fungicide application is made. (SB)
6. Capture 2 EC for Raspberry Crown Borer
The new 2005 label for Capture 2EC
has added raspberry crown borer for caneberries. This pest is a clearwing moth borer
and is a pest of blackberries and other cane fruits. The eggs are laid on the underside
of leaves in October and November. Feeding within the canes and crown can cause
both yield reduction and plant death. Capture can be applied at 6.4 fl oz/acre as
a post harvest (fall- late October to early November) or pre-bloom (spring- late
March to early April) drench application, but not both, directed at the crown of
plants in a minimum of 200 gal/acre. The fall application is considered to be the
most effective. (FH)
7. Pheromone Trap Catches and Biofixes
Nashville
(Davidson County) Pheromone Trap Catches for 2006
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)
| OFM | RBLR | OBLR | CM | GBM | VLR | BCW | DBM | |
| 3-1 (put out RBLR, OFM, VLR traps) | -- | 0 | -- | -- | -- | -- | -- | -- |
| 3-2 | -- | 3* | -- | -- | -- | -- | -- | -- |
| 3-9 | -- | 15 | -- | -- | -- | 0 | -- | -- |
| 3-13 | 0 | 50 | 0 | -- | -- | 0 | -- | -- |
| 3-21 | 0 | 71 | 0 | -- | -- | 0 | -- | -- |
| 3-28 | 0 | 15 | 0 | -- | -- | 0 | -- | -- |
| 3-29 (put out GBM, BCW, & DBM traps) | 0 | 5 | 0 | -- | -- | 0 | -- | -- |
| 3-30 | 0 | 4 | 0 | -- | 0 | 0 | 0 | 2** |
| 4-4 | 24*** | 34 | 0 | -- | 0 | 0 | 0 | 2 |
| 4-6 | 5 | 14 | 0 | 0 | 1 | 0 | 0 | 1 |
| 4-7 | 14 | 4 | 0 | 0 | 3**** | 0 | 0 | 0 |
| 4-11 | 12 | 10 | 0 | 0 | 1 | 0 | 0 | 1 |
| 4-17 | 39 | 9 | 0 | 0 | 23 | 0 | 0 | 4 |
| 4-18 | 6 | 0 | 0 | 0 | 1 | 0 | 0 | 0 |
| 4-24 | 49 | 0 | 14^ | 0 | 2 | 0 | 0 | 3 |
* Biofix for RBLR in Davidson County was March 2.
**Biofix for DBM in Davidson
County was March 30.
***Biofix for OFM in Davidson County is estimated to be April
3.
****Biofix for GBM in Davidson County was April 7.
^Biofix for OBLR in Davidson
County was April 24.
Bradley County Pheromone Trap Catches for 2006
| OFM | CM | |
| 3-29 | 3* | 0 |
| 4-3 | 26 | 0 |
| 4-5 | 0 | 1 |
| 4-10 | 16 | 0 |
| 4-24 | 17 | 17** |
*Biofix for OFM in Bradley County on March 29.
**Biofix for CM in Bradley County
on April 24.
Putnam County Pheromone trap Catches for 2006
| OFM | RBLR | OBLR | CM | VLR | |
| 3-21 (put out RBLR & OFM) | -- | -- | -- | -- | -- |
| 3-24 | 0 | 0 | -- | -- | -- |
| 3-27 | 0 | 0 | 0 | 0 | 0 |
| 3-31 | 2** | 12* | 0 | 2*** | 0 |
| 4-2 | 1 | 3 | 0 | 0 | 0 |
| 4-7 | 6 | 23 | 1 | 1 | 0 |
| 4-10 | 1 | 16 | 0 | 0 | 0 |
| 4-15 | 9 | 60 | 6 | 0 | 1 |
| 4-17 | 0 | 13 | 1 | 0 | 1 |
| 4-21 | 3 | 14 | 0 | 0 | 0 |
*Biofix for RBLR in Putnam County estimated as March 3 (trap not out early enough).
**Biofix
for OFM in Putnam county March 31.
***Waiting to verify biofix for CM, catch probably
too early.
Obion County Pheromone Trap Catches for 2006
| OFM | RBLR | OBLR | CM | VLR | |
| 3-13 | 1 | 49* | 0 | -- | 2*** |
| 3-21 | 0 | 40 | 0 | 0 | 0 |
| 3-27 | 1 | 2 | 0 | 0 | 0 |
| 4-3 | 2** | 13 | 0 | 2**** | 0 |
| 4-17 | 1 | 18 | 3^ | 1 | 5 |
| 4-25 | 7 | 0 | 0 | 0 | 4 |
*Biofix for RBLR in Obion County estimated to be on March 3 (trap not out early
enough).
**Biofix for OFM in Obion County on April 3.
***Waiting to verify
biofix for VLR in Obion County, catch probably too early.
****Waiting to verify
biofix for CM in Obion County, catch probably too early.
^Biofix for OBLR in Obion
County.
Additional Pheromone Trap Catches in Davidson County for 2006
Sod
Webworms (SWW), Armyworm (AW)
| SWW | AW | |
| 4-18 | 3* | 0 |
| 4-24 | 15 | 4** |
*Biofix for SWW in Davidson County for 2006.
**Biofix for AW in Davidson County
for 2006.
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 2006 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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