Fruit Pest News

Volume 6, No. 7  May 3, 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. Current Conditions and First Report

    2. Blackberry Fungicide Spray Program

    3. Blackberry Anthracnose

    4. Peach Leaf Curl

    5. Ferbam Fungicide Availability

    6. Apple: Petal Fall and First Cover Spray

    7. Stone Fruit: Plum Curculio and Oriental Fruit Moth

    8. Pheromone Trap Catches

1. Current Conditions and First Reports

Frigid weather just won't seem to let go! We continue to get below normal temperatures, although most areas have been spared hard freezes. Temperatures should become more seasonable toward the end of this week. Tomatoes do not look good as a result of all the cool weather.

First reports for the year during the past week: peach leaf curl -- April 27, Gibson County; cedar-apple rust and fire blight of apple -- May 1, Williamson County; black rot of grape -- May 1, Williamson County.

2. Fungicide Spray Program for Blackberries

The blackberry section of PB1197, Commercial Small Fruit Spray Schedules, is an index style guide in which pests are listed alphabetically. It is left up to the grower to tailor his/her own spray schedule, using the listed pesticides, because no single spray schedule fits all blackberry plantings. The spray schedule below is provided for those who may need some help in designing a program.

The rosette (double blossom) schedule is based on research conducted by Dr. Barbara Smith, USDA-ARS, who has found that Pristine and Switch are among the most effective labeled fungicides for rosette control. Primocanes need protection in rosette fields as long as infected blooms are open, which can last from the bloom period until after harvest ends. Remember that the benefits of a rosette spray program will not be seen until the following spring, when this year's primocanes come out of dormancy.

Rates can be obtained from PB1197 or the product labels. Always read and follow label directions.

 3. Blackberry Anthracnose

Anthracnose is characterized by dull brown, scabby, flattened, cracked drupelets on blackberry fruit. On ripe berries, recently-infected drupelets show a light purple discoloration. Leaf lesions are small, purple spots with white to tan centers. Spores produced by these spots can splash to the berries and produce the scabby berry condition. The fungus overwinters on leaf and berry debris and on canes.

I have found in my research trials with Benlate that control of blackberry anthracnose was best when applications were made at early bloom and at two-week intervals for two additional applications. In plantings with a history of anthracnose, this protectant schedule is recommended, using captan and a strobilurin (Pristine, Abound, or Cabrio). More frequent applications may be needed in excessively rainy weather. Do not apply a strobilurin more than twice consecutively before switching to captan. After harvest, floricanes should be removed and destroyed, to reduce the amount of carryover inoculum. (SB)

4. Peach Leaf Curl

Peach leaf curl is most severe when cool, wet weather occurs during bud swell and early leaf expansion. Spores of the causal fungus, which overwinter on bud scales and bark, wash onto the young leaf tissue in wet weather and initiate infections. Leaves become less susceptible as they age, and very little secondary spread of the disease occurs. Infected leaves become puckered, curled, thickened, and often show pink or reddish areas. Later in the season, upper surfaces of infected leaves turn gray. Infected leaves may wither and fall off in warm, dry weather. Fruit yields are often reduced because the tree’s energy is diverted into forming new leaves.

Applying a fungicide now will not be helpful, since no significant spread will occur. The disease can be controlled by a single fungicide application (bordeaux, chlorothalonil, copper) in the fall, after leaf drop. The application can also be effective when applied in late winter, but only if separation of the leaf scales has not been caused by a warm period during the winter. The most effective fungicides are ferbam (see the following article), chlorothalonil, thiram, ziram, and copper. In severe cases, try to improve tree vigor by reducing the fruit load and providing water during dry periods. (SB)

5. Ferbam Fungicide Availability

Ferbam fungicide will no longer be marketed for use on crops grown in Tennessee. Only cranberry and citrus uses were supported by the manufacturer during the reregistration process. Since these crops are not grown in Tennessee, Ferbam is no longer distributed in this area. If you still have old product on hand, you can use it according to the package label.

Ferbam was a valuable protectant for control of peach leaf curl. Other diseases controlled by this product include black rot of grape and summer rots of apple. (SB)

6. Petal Fall and First Cover Sprays for Apples

The petal fall and first cover sprays are very important for the control of several key pests. Plum curculio emerge from their overwintering sites in the spring when temperatures exceed 70 degrees F. They mate and can be in the tree at bloom. They can lay eggs under the fruit skin of the newly developing fruit very early and control at petal fall is critical in controlling the first generation of this pest. The Oriental fruit moth starts to become active before bloom and eggs begin to hatch at petal fall. The first generation larvae feed on shoot tips and inside apple fruit so the petal fall spray is important. The codling moth becomes active slightly later than Oriental fruit moth and the first generation eggs begin to hatch around the time of the first cover spray. (FH)

7. Plum Curculio and Oriental Fruit Moth in Stone Fruit

As with apples, early season control of plum curculio and Oriental fruit moth is extremely important and should have started at petal fall to 1% shuck split and continue in later sprays. Other pests to be looking for in the weeks ahead are stink bugs and scale crawlers. (FH)

8. Pheromone Trap Catches of Diamondback Moth, Cabage Looper and Armyworm

In Nashville at the Ellington Center, there was a big increase in the diamondback moth catch with 6 caught on Friday April 29 and 41 on Monday May 2. There were three cabbage loopers caught for the first time this season on April 29and four more on May 2. Armyworm moths were detected for the first time this spring with six found in the trap on May 2. (FH)

Nashville (Davidson County) Pheromone Trap Catches for 2005
Oriental Fruit Moth (OFM), Redbanded Leafroller (RBLR), Obliquebanded Leafroller (OBLR), Codling Moth (CM), Grape Berry Moth (GBM), Variegated Leafroller (VLR), Black Cutworm (BCW)

* 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 Phoromone Trap Catches for 2005

*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 Pheromone Trap Catches for 2005

*Biofix for RBLR in Putnam County on March 21.
**Biofix for OFM in Putnam County on April 6.

Obion County Pheromone Trap Catches for 2005

*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)

* 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 Pheromone Trap Catches for 2005*
Tufted Apple Budmoth (TABM)

*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

scbost@utk.edu

Frank Hale, Professor and Extension Entomologist

fahale@utk.edu

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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