Fruit Pest News
Volume 3, No. 22 September 3, 2002
An 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.
Fruit Pest News will be produced every two weeks until the end of the growing season.
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. General: Efforts to Extend the Use of Methyl Bromide
2. Strawberry Fumigant Prices
3. Apple: Cosmetic Storage Diseases
4. Apple: Prevent Storage Decays
1. Efforts to Extend the Use of Methyl Bromide
The EPA is currently accepting applications for exemptions from the phase-out rules for methyl bromide. In situations in which the loss of methyl bromide would create undue hardships (large-scale commodity market disruptions, lack of suitable alternatives) critical use exemptions (CUE's) may be granted. The exemption is for a period of three years, 2005-2007. If granted, the exemption amounts to a three-year extension of the January 1, 2005 deadline when methyl bromide must be phased out in the United States.
We are working on multi-state applications for CUE’s for tomatoes, cucurbits, peppers, strawberry fruit, and strawberry nursery production. We are basing our argument on one of the three possible criteria that may serve as a basis for a CUE: the lack of a technically or economically feasible alternative. Telone C-35 is one of the major alternatives, but is weaker against weeds and does not appear to be as consistent as methyl bromide.
These applications require some detailed information such as the amount of methyl bromide used each year from 1997 - 2001 and commodity yield and revenue from treated acreage for each of those years. Any uses that are not part of the multi-state applications mentioned above will require much additional paperwork. With just days remaining before the September 6 deadline, it would be difficult to complete any additional applications for exemptions. I would be glad to assist anyone who would like to prepare an application. Contact me by e-mail or at 615-832-6802. (SB)
2. Strawberry Fumigant Prices
Prices for our two main fumigants for strawberries, methyl bromide/chloropicrin 67/33 and Telone C-35, seem to be holding about where they were last year. I have been quoted $2.50 per pound for 67/33 and $18.50 per gallon for Telone C-35. These prices should be considered approximate. Prices in your area may be different. In plasticulture strawberry production, 67/33 is often applied at 400 pounds per treated acre and Telone C-35 at 40 gallons per treated acre. Since the fumigants are applied in rows that comprise about one-half the area of a field, these rates translate to 200 pounds and 20 gallons per actual acre for 67/33 and Telone C-35, respectively. The prices given above translate to $500 per actual acre for methyl bromide and $370 per actual acre for Telone C-35. (SB)
3. Cosmetic Apple Storage Diseases
Apple scab, sooty blotch, and flyspeck can develop after harvest, in storage.
Their appearance can reduce the marketability of the fruit. Although these
diseases first appear or increase in storage, they are the result of infections
that took place in the orchard before harvest. These diseases are favored by
wet, mild weather.
Storage
scab is sometimes referred to as 'pinpoint' scab because of its small size,
from barely visible up to 1/8 inch in diameter. The lesions are black and often
shiny because of the intact cuticle. They are circular and differ from scab
lesions that develop in the orchard by a darker color and a definite
border.
Late-season scab that becomes visible before harvest closely
resembles storage scab. Late-season scab lesions often remain viable in storage
and enlarge by forming a fringe of olive-green mycelia around the margin of the
scab spot.
At optimal temperatures for the scab, sooty blotch, and
flyspeck fungi (roughly 62º to 76º F), about 8 to 10 days are required for
symptom development after infection. Symptom development does not occur below
48º F.
Control of these cosmetic storage diseases must take place before
harvest; that is, infection must be prevented on the tree. In selecting
fungicides, preharvest intervals for the fungicides in question are a primary
consideration. Then consider what diseases to target. In orchards in which sooty
blotch and flyspeck is active, Benlate, Topsin M, Flint, or Sovran are good
choices. Benlate or Topsin M should be tank mixed with captan, not only for
resistance management purposes, but also for bitter rot control. Where scab has
remained or has become active, Dr. Turner Sutton, North Carolina State
University, suggests using dodine (Syllit) at 1.5 to 2 lbs/acre plus captan at 5
lbs/acre. Flint or Sovran would also play a valuable role. (SB)
4. Prevent Apple Storage Decays
The previous article discussed
cosmetic apple storage diseases. Other storage diseases such as blue
mold, caused by Penicillium expansum, and gray mold, caused by
Botrytis cinerea, involve decays that actually reduce marketable yields.
Unlike the cosmetic storage diseases, most of the decay disease infections occur
in storage, mostly through wounds. Control tactics differ for the two types of
storage diseases. However, certain late-season fungicide sprays in the orchard
can help reduce both types. Applied at 14 days before harvest, a tank mix of
either Benlate or Topsin M with either captan or ziram helps control storage
decays and sooty blotch and flyspeck. Chemical control after harvest has become
extremely limited. Sanitation practices are more important now than
ever.
If you have had problems in the past with storage decays, you are
encouraged to visit https://webmail.utk.edu/redirect?http://www.nysaes.cornell.edu/ent/scaffolds/2002/8.19.html#dl
for details on control. The article was written by David Rosenberger, Cornell
University. (SB)
The Fruit Pest News URL is: https://webmail.utk.edu/redirect?http://web.utk.edu/~extepp/fpn/fpn.htm
Contacts:
Steve Bost, Professor and Extension Plant Pathologist
Frank Hale, Associate 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
