Apple Pest Report: Friday, June 22, 2007
Vol. 15 No. 12
Apple Scab
Primary scab ascospore releases are done for the
year. The only infective scab
spores from now on are those on existing lesions in the orchard.
Even though it seemed to be
a relatively easy year for primary scab control, and unusually high percentage
of orchard blocks checked recently are showing at least some scab. Two thirds of the blocks checked on June
18-22 (Monday-Friday) had at least one scab-infected leaf per 100 shoots. More than half had 8 or more scabby
leaves (and a third had more than 18), indicating need for eradication
treatment and 7-10 day fungicide intervals to maintain solid protection for the
next 4 weeks until existing lesions exhaust their supply of secondary spores.
Concern is increased by the
fact that a new crop of scab lesions could start appearing around
Wednesday-Thursday June 27-28. That
is when second generation infections from the final primary scab infection
period June 1-5 would have had enough time to develop visible spots on
leaves. The good news is that if
you thoroughly scout your orchard on or after June 28 and do not find scab then
it is safe to assume that scab control was effective and switch to a more
relaxed fungicide schedule based on keeping flyspeck, sooty blotch, and other
summer diseases in check.
If
you are dealing with secondary scab infections, a regularly updated table of
post-primary scab fungicide interval recommendations based on weather at
Highmoor Farm and vicinity may be of use if rainfall at your locations is
similar to Highmoor Farm. See http://pronewengland.org/AllModels/MEmodel/me-Monmouth-SecondaryScabSpray.htm.
Fire
blight
A
third Maine orchard with a minor degree of blossom blight was reported this
week. More extensive fire blight
was found in a NH orchard.
Shoot
blight arising from the May 27-28 infection period could begin showing up
around Tuesday, June 26. Shoot
blight arising from overwintered fire blight cankers would begin appearing
around July 3.
So
far it looks like the May 27-28 weather conditions did not lead to any serious
fire blight infections in Maine, but it is too early to stop looking. Frequent checking is important because
if fire blight strikes do appear, a quick response helps to limit severity on
affected trees and to reduce spread to other trees.
Flyspeck and
Sooty blotch
If you control flyspeck,
you won’t get sooty blotch, so management recommendation are based on
flyspeck. Because flyspeck
primarily overwinters on alternate host plants in the orchard border, risk of
fruit infection does not increase until flyspeck colonies on border row hosts
start releasing second generation spores.
This is estimated to begin around June 29 at Highmoor Farm.
Growers with scab under
control have often let fungicide coverage lapse in early July while waiting for
the next spray trip required for other reasons (i.e. calcium or insecticide for
apple maggot). This has not led to
flyspeck problems, and so it seems to me that the risk of flyspeck infection in
early July is quite low. That the
first flyspeck infections on unsprayed trees usually do not appear until
mid-August supports this notion.
But I must emphasize that it is only a notion, not a scientifically
tested idea. To play by the current
version of fungicide interval guidelines, fungicide coverage should be renewed
when 14-21 days (depending on material) or two inches of rain occurs. Tables updated twice daily to help with
evaluating fungicide respray intervals are available at http://pronewengland.org/AllModels/MEmodel/RADARME-Monmouth.htm#FLYSPECK
Flyspeck risk will increase to a higher
level in early August. (The current
estimate based on climatology August 7, but it is too early for a meaningful
forecast). Where there have been
problems with flyspeck in Maine orchards is when the final fungicide
application was not late enough to protect against August and early September
flyspeck infections that then had enough subsequent leaf wetness hours to become
visible before harvest. Flyspeck development usually takes about 30 days, but
can be quicker with prolonged wet, cloudy weather. The best flyspeck protection is had by
reserving a strobilurin application for August 15 or later, and being willing
to reapply fungicide if heavy rains remove fungicide protection before
September 10.
Insects and Mites
Rose
chafers beetles were feeding on backyard peach and apple trees. Japanese beetles will start their annual
feasting in a few weeks.
Apple
and thorn skeletonizer appeared in a couple of places with unsprayed apple
trees. Usually we don’t see these until second generation in
mid-August, but first generation is out now. They aren’t officially
leafrollers but they roll leaves and wiggle like crazy when picked up.
They
are primarily an aesthetic pest but can defoliate an entire limb.
Photo
by Kirin Elliot, Oregon State University.
A common species of stink
bug, Banasa dimdiata was numerous on pears and apple fruit.
European red mites have
been very low in monitored blocks so far.
Mite populations could increase next week as 2nd generation
egg hatch continues and early hatched nymphs become more visible as
adults. Those 2nd
generation adults will begin laying 3rd generation eggs starting
roughly around June 27 at Highmoor Farm.
Portal miticide (similar to
Fujimite) is now registered for use in Maine.
It will be time to set
apple maggot traps soon. When
threshold is reached and control is needed, Imidan, Calypso, Assail, and
pyrethroids are all effective options.
Other News
McIntosh Maturity Forecast Dates
The
early season forecast for the date when McIntosh fruit will reach starch index
4.0, which signals that fruit are ripe enough for long-term CA storage, is
based on the Full Bloom dates and temperatures during the 30 days after Full
Bloom. For Highmoor Farm, the
estimated date is September 18.
The estimated date for
McIntosh fruit to reach Starch Index 6.0, which signals that fruit maturity is
at maximum level recommended for long term CA storage, is September 26. While these formulas have generally worked
well in the past, they are by no means a replacement for orchard specific
maturity testing as harvest nears.
Workshop
Announcement
Apple growers in some of the
other Northeast states get government support for IPM activities and
expenditures. It would be nice to have
that working for us in Maine. The
following workshop is a step in that direction. While the workshop is about vegetable
and small fruits, even apple growers who do not grow those crops might it find
it an interesting introduction to Natural Resource Conservation Service (NRCS)
farm support programs.
On
June 25, the Maine Department of Agriculture will host an on-farm workshop that
demonstrates conservation-based integrated pest management (IPM) practices for
vegetable production. Funded by USDA-CSREES through the Northeastern IPM
Center, this workshop will focus on using IPM practices to promote NRCS
conservation goals, with the objective of helping growers improve crop yield and
pest control while minimizing environmental impacts. Participants will learn
how IPM and conservation practices complement one another and benefit vegetable
production, and how growers can earn financial assistance from NRCS for using
IPM practices. Topics will include: cover cropping, insect and weed
identification and management, soil quality, economic thresholds, pest
monitoring, zone till demonstration, conservation planning and practices, and
plant nutrition and health.
The workshop will be held June 25, 2007 from 9:00 AM to 3:30 PM at two
vegetable farms located in the central coast region in Nobleboro and Jefferson,
Maine. Contact Dr. Kathy Murray,
Maine Department of Agriculture for details: 207-287-7616, kathy.murray@state.me.us
Growers will learn about
different IPM practices and their conservation benefits, and how NRCS
conservation programs can help their farms.
EPA List of Pesticides for Testing as Endocrine Disruptors
The EPA has
published for public comment a list of pesticide active and inert ingredients
to be tested for activity as endocrine (hormone) disruptors. EPA gave priority to
materials with greatest potential human exposure through resides on food or
through occupational use. Materials
on this
list should NOT be construed as known or likely endocrine disruptors. Nothing
in the approach for generating the initial list provides a basis to infer that these
chemicals are suspected to interfere with the endocrine systems of humans or
other species, and it would be inappropriate to do so.
After considering comments on this draft list of chemicals, EPA
will issue the final list of chemicals to be tested. Other details such as time
frame and test methods have not yet been announced. More
information is available at http://pmep.cce.cornell.edu/profiles/FFDCA_draft_0607.pdf
This new testing regime has already been in the media, and may
generate questions from customers.
Here is a list of pesticides used on apple and other tree fruits that
appear on the EPA list.
|
Tree-fruit pesticide active ingredients
on the list of materials proposed for initial testing for endocrine disruptor
activity |
|
|
Fungicides |
|
|
captan (Captec) |
myclobutanil (Nova) |
|
chlorothalonil (Applause, Bravo, Concorde, |
propiconazole (Orbit) |
|
iprodione (Rovral) |
tebuconazole (Elite) |
|
mefenoxam = metalaxyl (Ridomil) |
triadimefon |
|
Herbicides |
|
|
2,4-D |
norflurazon (Solicam) |
|
dichlobenil (Casoron) |
simazine (Princep) |
|
glyphosate |
|
|
Insecticides & Miticides |
|
|
abamectin (Agri-Mek) |
fenbutatin oxide
(Vendex) |
|
Azinphosmethyl (Guthion) |
Imidacloprid (Provado) |
|
Binfenthrin (Brigade) |
malathion |
|
Chlorpyrifos (Lorsban) |
methidathion (Supracide) |
|
Cyfluthrin (Baythroid) |
methomyl (Lannate) |
|
Diazinon |
oxamyl (Vydate) |
|
dicofol (Kelthane) |
permethrin (Ambush,
Pounce) |
|
dimethoate (Dimate) |
phosmet (Imidan) |
|
endosulfan (Thionex) |
piperonyl butoxide
(present in some pyrethin formulations, combined with rotenone in Pyrenone) |
|
esfenvalerate (Asana) |
|
Summer Weather Outlook
As
of June 22, the July 1-month outlook is for slightly increased chance of
above-normal temperatures in Maine, and a stronger tendency for above-normal
temperatures for the 3-month July-September period. The July precipitation outlook is
normal, and the 3-month precipitation outlook is slightly above normal.
New Plant Hardiness Zones Maps
The
National Arbor Day Foundation (NADF) has published an updated Plant Hardiness
Zone map that redefines some areas in Maine from zone 4 to zone 5, and calls
the extreme southern tip of Maine zone 6.
The NADF map is based on 15 years of minimum winter temperatures. The USDA is working on an update of
their 1990 plant hardiness zone map which will be based on more
observations. The USDA map is
supposed to be released sometime in 2007.
You can see the NADF map for the entire U.S. at http://www.arborday.org/media/mapchanges.cfm.
Plant Hardiness Zone
Maps
USDA 1990 NADF 2006 Zone changes in NADF map
Sincerely,
Glen
Glen Koehler
Pest Management Office
491 College Avenue
Orono, ME 04473
Voice: 207-581-3882
Email: gkoehler@umext.maine.edu
Web: PRONewEngland.org
Fax: 207-581-3881
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