Fruit Pest News

In This Issue:

1. Current Crop Development
2. Apples: Early-Season Fungicide Sprays
3. Small Fruit: Changes in Disease-Control Recommendations
4. Apples: What's New for Insect Control Recommendations?
5. Apples: Pheromone Trap Catches

1. CURRENT CROP DEVELOPMENT

Temperatures remained very cool the past week and crop development is generally behind normal for this time of year. We have not had 70 degrees since early March. Most apple varieties are at tight cluster, peaches are in bloom, and matted row strawberries are yet to begin bloom. Plasticulture strawberries were in bloom during last week's 20-degree weather. Things will change this week, with warm weather predicted. Cedar-apple rust spores will begin to be released this week, as I saw cedar galls with the horns, ready to turn orange and release spores during the warm showers that are forecast for this week. (SB)

2. EARLY-SEASON APPLE FUNGICIDE SPRAYS

The recent cool weather has slowed the development of both the trees and the pathogens. Many trees are now at tight cluster. For many orchards, this is the time for the first fungicide application. Scab control at this time is a must. There are several different strategies for scheduling scab sprays. The selection of a spray program depends on factors such as other disease organisms present and the ability to obtain good coverage of the trees with the sprays. If cedar-apple rust or powdery mildew are a threat, it is probably best to control scab with a sterol-inhibiting fungicide (Nova, Procure, or Rubigan), because control of all three diseases would be obtained. Tank mixing with mancozeb or captan would improve the protectant ability and discourage the development of resistance to the sterol inhibitor (SI). The 3 to 4 day curative activity of the SI fungicides makes them useful at tight cluster in case some scab infections occurred prior to that time. The SI/protectant combination allows you to space the applications 7 to 10 days apart. Where cedar-apple rust is a problem, mancozeb or ziram should be used as the protectant. The strobilurin fungicides Flint and Sovran can be used in lieu of the SI's, but I recommend reserving these materials for use during the summer. They may only be applied 4 times per year, and they play a more valuable role during the summer than during the spring. (SB)

3. CHANGES IN DISEASE CONTROL RECOMMENDATIONS FOR SMALL FRUIT

As reported in the March 19 issue of Fruit Pest News, this year's version of the Commercial Small Fruit Spray Schedules (University of Tennessee PB 1197) is available at county Extension offices. It can also be accessed on the Entomology and Plant Pathology website at http://web.utk.edu/~extepp/pubs/pb1197.pdf. Following are the major changes made in the disease control recommendations:

Blackberries - Added Nova 40W for control of orange rust and powdery mildew. Nova will also control yellow rust and cane and leaf rust. The labeled rate is 1.25 to 2.5 oz/acre, applied at 10 to 14-day intervals beginning as early as bud break, depending on the disease(s) to be controlled. For orange rust control, begin applications in April, before orange pustules appear on undersides of leaves. Nova does not benefit systemically infected plants. Do not apply more than 10 oz/acre per growing season. Nova may be applied up to the day of harvest.

Raspberries - Added Nova 40W for control of leaf spot, the rusts, and powdery mildew. The labeled rate is 1.25 to 2.5 oz/acre, applied at 10 to 14-day intervals. For leaf spot control, begin sprays in late spring or earlier, if disease appears earlier. For powdery mildew (not a common problem in Tennessee) control, make first application at white blossom bud stage and repeat 10 to 14 days later. Do not apply more than 10 oz/acre per growing season. Nova may be applied up to the day of harvest.

Strawberries - Added Nova 40W for control of powdery mildew, common leaf spot, and Phomopsis leaf blight. The labeled rate is 2.5 to 5.0 oz/acre, applied at 14 to 21-day intervals. Do not apply these rates more often than every 14 days. Nova may be applied up to the day of harvest. Do not apply more than 30 oz/acre per year.

Strawberries - Added a reduced rate, 1.0 lb/acre, of Elevate 50WG, for use in tank mixes with other Botrytis fungicides, in accordance with a Section 2(ee) label. The Section 3 labeled full rate of 1.5 lb/acre, used last year, is still in effect for stand-alone use of Elevate. A tank mix of Elevate at 1.0 lb with captan or thiram will provide anthracnose control without compromising Botrytis control, as compared to 1.5 lb of Elevate alone. (SB)

4. WHAT'S NEW FOR APPLE INSECT CONTROL RECOMMENDATIONS?

There have been many changes concerning pesticides the last few years. Some are the result of the Food Quality Protection Act of 1996. While we have lost some uses of insecticides, the agrochemical industry has been busy producing lots of new chemistry. The Integrated Orchard Management Guide for Commercial Apples in the Southeast for 2001 reflects a good portion of these changes. I will be mentioning some of the new insecticides that have been included in the management guide. If you need more information on any of these pesticides, refer to the section toward the back of the management guide, starting on page 49 for fungicides and bactericides, page 52 for insecticides and miticides, and page 55 for herbicides. There is a paragraph written for each pesticide that gives more detail about its use.

Prebloom Period -- Lorsban 4EC and Lorsban 40W can be used only during the prebloom period and will control San Jose scale, climbing cutworms, and nonresistant rosy apple aphid.

Green Tip to 1/2 Inch Green -- A new insecticide added to the list is pyriproxyfen (Esteem 0.86 EC), by Valent. Esteem interrupts normal development of eggs and immatures so that the insects do not complete development. Esteem is used at 13-16 oz/acre with a superior type or highly refined summer oil applied dilute for control of San Jose scale and rosy apple aphid. Note that in some blocks in the Southeast, applications of Lorsban, Asana and Ambush no longer control rosy apple aphid due to resistance. There is a 12 hour re-entry interval (REI) and a 45 day preharvest interval (PHI).

Tight Cluster to Pink -- Fenpropathrin (Danitol 2.4EC), by Valent, has been added. This pyrethroid insecticide is used at 4 oz/100 gal. (10.6-21.3 oz/acre) for control of rosy apple aphid or spotted tentiform leafminer. In some blocks in the Southeast, rosy apple aphid is resistant to Thiodan/Phaser, Ambush and Asana. For Danitol 2.4EC, there is a 24 hour REI and a 14 day PHI.

Petal Fall -- Added to the list is Danitol 2.4EC at 2.6-5.3 oz/100 gal. (10.6-21.3 oz/acre) for control of European red mites, spotted tentiform leafminer, and white apple leafhopper. Also, add Carzol 92S at 2.4 oz/100 gal. (4-16 oz/acre) for control of these same pests. The REI for Carzol is 10-16 days. Do not apply Carzol after petal fall. Note that Danitol can control labeled insects as well as mites. I would rather see it used prebloom.

Also at petal fall, hexythiazox (Savey 50WP), by Gowan, has been added to the list at 3 oz/acre for control of European red mite. It is toxic to European red mite eggs and larval stages, and will not directly affect mite predator populations. There is a 12 hour REI and a 28 day PHI. Apollo and Savey are both most effective if applied at petal fall or first cover. To minimize the potential for resistance development, do not use Savey or Apollo in the same or successive years.

Another new insecticide added at petal fall is indoxacarb (Avaunt 30 WG), by Dupont. Avaunt affects the nervous system of insects, but in a different manner than other insecticides. It is used at 5-6 oz/acre for control of plum curculio, Oriental fruit moth, and white apple leafhopper. There is a 12 hour REI and a 28 day PHI.

Esteem 0.86EC at 13-16 oz/acre has been added for control of San Jose scale. Danitol 2.4EC at 2.6-5.3 oz/100 gal. (10.6-21.3 oz/acre) has been added for control of rosy apple aphid.

First Cover -- Added methoxyfenozide (Intrepid 2F), by Rohm and Haas, for control of codling moth at 10-16 oz/acre. When ingested by larvae, it initiates a premature molt in which the insect cannot shed its old cuticle and dies from dehydration and starvation. Methoxyfenozide is an analog of tebufenozide (Confirm) with the same mode of action and spectrum of activity; hence, for resistance management practices, Intrepid and Confirm should be considered the same insecticide. There is a 4 hour REI and a 14 day PHI. If using Confirm or Intrepid for first generation codling moth, 2 applications at 14-day intervals should be made, the first at 150-200 degree days.

Added Danitol 2.4EC at 16-21.3 oz/acre for control of codling moth. Danitol is also listed for control of the same pests as at petal fall.

Added Avaunt 30 WG at 5-6 oz/acre for control of codling moth. Avaunt is also listed for control of the same pests as at petal fall.

Second Cover and Later Sprays -- Added Danitol 2.4EC at 16-21.3 oz/acre for control of Oriental fruit moth, tufted apple bud moth, apple maggot, white apple leafhopper, and potato leafhopper.

Added Intrepid 2F at 6-12 oz/acre for control of tufted apple budmoth, at 10oz/acre for control of redbanded leafroller, and at 10-16 oz/acre for control of lesser apple worm.

Comstock mealybug has become a problem in some orchards in the Southeast where OP use has been reduced or eliminated and/or where postbloom pyrethroid use has increased. Diazinon AG600, Diazinon 50WP and Dimethoate 4EC/400 are recommended for control.

Woolly apple aphid has become more of a problem in many areas in recent years. Above-ground infestations are of greatest concern on younger trees. Dimethoate 4EC/400 is recommended for control. (FH)

5. PHEROMONE TRAP CATCHES

Redbanded leafrollers (RBLR) and Oriental fruit moths (OFM) have been active in Tennessee. Obliquebanded leafroller (OBLR) and codling moth (CM) have not been caught yet.

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