Fruit Pest News

March 19, 2001

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. Strawberry Disease Alert
2. Fruit Spray Guides: Availability
3. Southern Appalachian Apple IPM Project
4. Small Fruit: Status of Switch® Fungicide
5. Home Fruit Spray Guide

1. STRAWBERRY DISEASE ALERT

There is cause to be on the lookout for Phytophthora and anthracnose in plasticulture fields this spring. Last fall, there were two known cases of Phytophthora crown rot and one case of anthracnose in Tennessee. The anthracnose occurred in one of the Phytophthora fields. While these disease organisms can be contracted from the field envrionment, it is quite possible that the transplants were the source of infection, i.e. the diseases were shipped in on the plants. The anthracnose was Colletotrichum gloeosporioides, a species we do not often see on strawberries. Our predominant species is C. acutatum.

Scouting: When looking for Phytophthora and anthracnose, remember that they usually do not express themselves until near harvest time. If the the spring weather is unusually warm, you may see symptoms earlier. In general, Phytophthora crown rot is characterized by necrotic leaves and wilting when the fruit load begins to stress the plant. Anthracnose is characterized by a circular-shaped lesion on the berry and dark lesions on petioles and stolons. In very warm springs, anthracnose can cause a blighting of the blossom clusters.

Control: On the chance that your plants may be infected with Phytophthora, you may want to make an application of Ridomil Gold EC now. It is injected into the drip irrigation at the rate of 1 pint per treated acre. An actual acre would only receive 0.6 pint if the beds are 3 feet wide and spaced 5 feet apart, because only 60% (3/5) of the ground would be treated.

Anthracnose can be suppressed by including an anthracnose material with each spray (every 7-10 days). Captan and thiram have activity against C. acutatum, while captan, thiram, Benlate, and Topsin M have activity against C. gloeosporioides. Quadris is effective against both species, but is not labeled for strawberries at this time (a Section 18 label has been applied for). (SB)

2. FRUIT SPRAY GUIDES: AVAILABILITY

The status of 2001 publications related to pest control for fruit crops in Tennessee are as follows:

2001 Commercial Small Fruit Spray Schedules (University of Tennessee PB 1197) -- Printed, bound copies are available at county Extension offices. This publication can also be accessed on the Entomology and Plant Pathology website at http://web.utk.edu/~extepp/pubs/pb1197.pdf .

2001 Integrated Orchard Management Guide for Commercial Apples in the Southeast (regional publication) -- Printed, bound copies are available at county Extension offices. Also available on the internet at http://web.utk.edu/~extepp/redbook/c-apple.pdf .

2001 Southern Peach, Nectarine, and Plum Pest Management and Culture Guide (regional publication) -- Printed, bound copies are available at county Extension offices. Plans are to make this publication available on the iternet, as it was last year, but it has not yet been posted. I will let you know when it is available there. (SB)

3. SOUTHERN APPALACHIAN APPLE IPM PROJECT

The Southern Appalachian Integrated Apple Orchard Management Research and Implementation Project was formed to address the concerns brought about by the Food Quality Protecton Act (FQPA). Finding suitable pest control programs to replace the pesticides threatened by the FQPA is a chief objective of the program, which is centered in North Carolina.

The project assists growers in using and experimenting with reduced-risk replacements for the FQPA-targeted organophosphate (OP) and carbamate insecticides and those fungicides classified as "probable human (B2) carcinogens." Growers participating in the program attempt to reach a goal of a certain reduction in the number of applications of the threatened pesticides. Those who grow for the processing market, which comprises a large portion of the North Carolina acreage, strive for a greater reduction in OP and B2 usage than fresh market growers. The high cosmetic standards for fresh market apples dictate a lower tolerance for damage. The insect management program is similar to the one that Frank Hale reports on in this newsletter. The reduced-risk chemicals relied on in the Southern Appalachian project include the insecticides Confirm and SpinTor, and the strobilurin fungicides Flint and Sovran.

The website of the project can be accessed at http://fletcher.ces.state.nc.us/programs/apple/apple/apple.htm . It contains a newsletter and other useful information for apple growers. (SB)

4. STATUS OF SWITCH® FUNGICIDE FOR STRAWBERRIES AND BRAMBLES

We sometimes get inquiries about the status of Switch fungicide, which was originally scheduled for registration on strawberries last year. Swith will not receive registration on strawberries or brambles until 2002 because of some residue problems on rotation crops, for which additional data is needed.

Switch is an effective Botrytis control material that also has good activity against strawberry anthracnose. (SB)

5. HOME FRUIT SPRAY GUIDE

The University of Tennessee publication, Disease and Insect Control in Home Fruit Plantings (PB 1622) has been revised and is available at county Extension offices. The revised version has not yet been posted on the UT website, but should be there soon. Two changes were made in the disease-control recommendations in the new version:

Benomyl was removed because of the unavailability of this product for homeowner use. It is no longer produced for this market, and the label of the commercial benomyl product, Benlate, states that it is not for use in home plantings.

Immunox®, a myclobutanil product from Spectracide, has been added to the tree fruit and grape recommendations. Immunox will replace benomyl for many uses, such as scab and powdery mildew of apple and brown rot of stone fruits; plus, Immunox will add effective control of cedar-apple rust and grape black rot. Immunox is sold in one-pint containers and is readily available at retail outlets. Note that Immunox Plus® is a different product in that it contains an insecticide, in addition to myclobutanil, and is not labeled for use on food plants. (SB)

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, Associate Professor and Extension Entomologist
fahale@ext1.ag.utk.edu

Both authors available at:
615-832-6802
fax 615-781-2568
Plant and Pest Diagnostic Center
5201 Marchant Drive
Nashville, TN 37211