Fruit Pest News
Volume 6, No. 1 March 15, 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 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.
Welcome! to the first issue of the sixth volume of Fruit Pest News. We hope the newsletter is helpful to you, so please let us know of any changes we can make to better meet your needs. One of our most important functions is to keep you apprised of pest occurrences in the state. So please let us know when you see a disease or insect for the first time for the year, or if you have an unusual outbreak. We won't use your name. Our contact numbers are at the end of each issue of the newsletter.
Fruit Pest News also brings you research reports, pesticide registration changes, and other pest-related news. The newsletter will be compiled each Monday and should be available for viewing on the Internet the following day. There will be a new issue each week through mid-July, then every two weeks through early October.
In This Issue:
1. Current Conditions
2. Tree Fruit: Dormant and Delayed Dormant Oil Sprays
3. Tree Fruit: Pheromone Trap Time Again
4. Strawberry Spray Schedule
5. Strawberry Field Sanitation for Gray Mold Management
6. All Fruit: New Fungicide Recommendations for 2005
1. Current Conditions
We appear to be bringing to a close yet another mild winter. Spring is breaking, as early-season flowers begin to show. With the exception of Saturday's upper-70's, the weather has been cool, and most fruit plants are not yet in bloom. The earliest blueberry cultivar in the planting at the Plant and Pest Diagnostic Center at Nashville is O'Neal. It makes for a good indicator of the earliness of spring. This year, the first open bloom was around March 1, which is slightly ahead of average. Redhaven peaches are at the red calyx stage of swollen bud and blackberries are at 1/2 inch green tip. (SB)
2. Dormant and Delayed Dormant Oil Sprays
We continue to stress the importance
of using superior oil as Dormant and Delayed Dormant sprays because they are relatively
inexpensive and quite effective. On peaches, nectarine or plum, oil helps control
San Jose scale and white peach scale as a Dormant or Delayed Dormant spray. Dilute
applications should idealy be made 10-14 days apart. For dormant trees, oil can be
applied at 2-4% by volume (2.5 to 5 gallons per 125 gallons of spray). For partially
dormant trees, apply 1 to 1.5% by volume (1.25 to 2 gallons per 125 gallons of spray).
Use 125 gallons of spray per acre for mature trees.
At Delayed Dormant to
1 to 5% bud swell on peaches, nectarine or plum, use oil at 1 to 1.5% by volume.
Lorsban 4E, Esteem 35 WP, or Supracide 2E can be added to the oil to strengthen performance
against scale. Pyriproxyfen (Esteem) applied with oil at delayed dormant is our best
scale control material. Lorsban also offers some suppression of lesser peachtree
borer. Do not use oil after 5% pink bud.
European red mite eggs, rosy apple
aphid eggs and San Jose scale are reduced on apples by applying oil at Green Tip
to 1/2 Inch Green. Insecticides can be applied with the oil to help control scale
and climbing cutworms. These insecticides include Lorsban 4E, Supracide 2E, Esteem
35WP, Diazinon 50WP, Danitol 2.4EC, Asanal XL, or Ambush 2E. Esteem will control
San Jose scale if applied before 1/2 Inch Green. See the 2005 Integrated Orchard
Mnagement Guide for Commercial Apples in the Southeast for rates and effectiveness
ratings. The pyrethroid insecticides Asana XL and Ambush will not help control mites
or scales. Also, if you are having scale problems, avoid using pyrethroid insecticides
during the growing season, because they can kill scale predators and parasitoids
that normally would help manage scale populations. There are new insecticides and
miticides available for tree fruit, but why not first try to get all you can out
of the oil sprays. (FH)
3. Pheromone Trap Time Again
Pheromone traps will
be mailed to our cooperators on March 15. On Friday, March 11, I put out a new redbanded
leafroller (RBLR) trap with fresh pheromone at the Ellington Agricultural Center
in Nashville. There were16 RBLR moths in the trap by Monday, March 14. Temperatures
in the high 70s on Saturday sure got the moths flying. The other pheromone traps
will be put out soon. (FH)
3. Strawberry Spray Schedule
Below is a recommended spray schedule to follow for springtime disease control in strawberries. The exact design of a spray schedule can vary depending on disease control needs and products available. However, the principles illustrated below should serve as a good general guide for management of the two most common diseases, Botrytis and anthracnose.
|
Application no. (Weekly intervals) |
Product |
Discussion |
|
If anthracnose is not present |
||
|
1 (early bloom) 2 3 4+ (through harvest) |
Elevate Switch Pristine (repeat sequence; program may be relaxed somewhat during harvest) |
Botrytis is the primary target. This fungus is known for "getting used to" a fungicide and developing resistance to it. Try to include 3 chemical classes, as in the example, to keep Botrytis off-balance. The new fungicide Scala represents a 4th chemical class for Botrytis control. It does not matter what order these materials are used in.
|
|
If anthracnose is present |
||
|
1 - 4+ Harvest period 1 2 3+
|
Follow above schedule during bloom, with captan or thiram included in each application.
Captan plus either Quadris, Cabrio, or Pristine Captan alone (repeat harvest sequence)
|
The activity of anthracnose, if present, is low during bloom. The use of captan or thiram will provide adequate protection during this time. Thiram and captan are interchangeable because they are equally effective against Botrytis and also against anthracnose. Thiram has an advantage over captan in that thiram has a deer and rabbit repellency property. Thiram does not fit the harvest period because of a 3-day preharvest interval. CaptevateŽ is a premix of captan and Elevate, and may be used in lieu of a tank mix. NOTE: The strobilurins (Quadris, Cabrio, Pristine) are limited to 5 applications per crop, either individually or collectively. For this reason, beware of using the strobilurins during bloom because you don't want to use up part of your allotment before the harvest period, which is a critical time for anthracnose control. |
(SB)
5. Strawberry Field Sanitation for Gray Mold Management
Many plasticulture strawberry producers remove senescent (dead and dying) leaves and stems from their plants before first bloom in the spring. This practice (leaf sanitation) eliminates a food base for the Botrytis fungus and, thus, reduces the amount of spores available for infecting the blossoms. This practice should be done before bloom, because blooms would be damaged in the process. Recent research has cast some doubt on the usefulness of leaf sanitation, but it is still practiced by many growers. (SB)
6. New Fungicide Recommendations for 2005
The following national registrations have occurred within the last year and have been added to our recommendations for 2005.
Grapes
Stone fruits (except cherries)
Pome fruits
Strawberries
(SB)
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