UNIVERSITY OF CALIFORNIA
COOPERATIVE EXTENSION
TREE TOPICS
INFORMATION FOR TREE FRUIT AND NUT GROWERS
IN CALIFORNIA’S CENTRAL COAST REGION
___________________________________________________________________________
APRIL 29, 2003
VOLUME 28, ISSUE 3
IN THIS ISSUE:
►CODLING MOTH: WALNUTS, APPLES
►PEACH TWIG BORER: APRICOTS
► FOGSPOT AND CRACKING: APRICOTS ►UCCE BUDGET
► ORGANIC WALNUT HUSK CONTROLS
CODLING MOTH: WALNUTS, APPLES
Codling moth is generally the most significant pest of apples and walnuts in the Central
Coast growing region. This is the larva or “worm” that bores into apples or walnuts. Codling
moth spray timing is determined utilizing a computer model which is available at our UC
IPM website at http://ipm.ucdavis.edu. To start the model, you need to know the
biofix. The biofix is the day on which we first have consistent pheromone trap catches and
the sundown temperature exceeds the 62 degrees F, the temperature that is required for
mating.
The biofix for San Benito and Santa Clara Counties for codling moth in apple and walnut
orchards was March 29. The biofix for apples in Santa Cruz and northern Monterey Counties
was not established as of April 28. Trap counts in southern Santa Clara County and in
northern San Benito County have been moderately high despite cool weather. Traps from
Hollister and south to Tres Pinos have recorded lower trap counts while traps in Santa Cruz
County have had very low counts.
Spray dates for conventional insecticides are at 300 degree-days for walnuts and 250-300
degree-days for apples. Insect growth regulators are generally applied a little earlier (for
example: 200-250 degree-days for Confirm on walnuts). Pheromone mating disruption
dispensers should be placed in the orchard by the time of the biofix.
(continued)
U.S. DEPARTMENT OF AGRICULTURE, UNIVERSITY OF CALIFORNIA AND SAN BENITO COUNTY COOPERATING
The following chart for spray timing is based upon the March 29 biofix, actual temperatures
through April 27 and average temperatures after April 27. Walnuts should also be ½ inch in
diameter – late-blooming varieties such as Howard, Chandler and others are very late
blooming this year and probably will not need control measures until the 1B flight. Earlyblooming varieties such as Payne and Serr are variable in bloom but some nuts are already at
½ inch in diameter. The need for a spray may depend on whether you had significant codling
moth damage at harvest last year (more than 1 or 2 %), your trap counts, past experience, and
whether the weather turns warm. Cool weather generally means reduced mating and egglaying.
Hollister
Ausaymas/North San Benito County
Morgan Hill
250 DD
May 6
May 2
May 4
300 DD
May 11
May 7
May 8
I will provide a biofix for Santa Cruz and northern Monterey County apples in my May
newsletter. You may also try calling the Apple Hotline at 831-763-8002, which has both
codling moth, and scab forecasts.
FOGSPOT AND CRACKING: APRICOTS
Fogspot and green fruit cracks are very common in local apricot orchards this year. Fogspot
causes reddish-purple spots on the fruit that may run together and form patches that turn dark
and eventually scab over. The affected area has a rough surface. There are no spots on the
leaves such as with shothole disease. The fungus Alternaria is often associated with fogspot
but has not been proven to cause the disease. Fungicides have had variable efficacy and there
are no currently recommended control measures. Moisture in late March through mid-April
seems to be related to fogspot incidence.
Cracking of fruit is often the result of rapid growth from excess nitrogen, rapid temperature
increases or rainfall. In March, the temperature reached as high as 87 degrees F. I suspect this
unusual occurrence is related to the apricot fruit-cracking problem. It occurred before the
April rains. During hand-thinning, cracked fruit could be preferentially removed but since
most apricots are thinned with sticks, this is not practical except near the ground.
ORGANIC WALNUT HUSK FLY CONTROLS
The lack of organically acceptable controls for walnut husk fly has been a major problem for
local walnut growers in recent years. Beginning in the mid-1990’s, I began looking for
control measures that might provide some relief for this problem. My research along with
that of my colleague, Extension Specialist Bob Van Steenwyk, has resulted in the availability
of three effective organically acceptable walnut husk fly controls for this season. Two are
(continued)
spinosad compounds from Dow Agrochemicals – GF-120 NF Naturalyte Fruit Fly Bait
(which is already registered) and Entrust (due to be registered in June). GF-120 includes a
bait, Entrust would need to be mixed with a bait. Full coverage is not necessary since these
are bait sprays that attract the flies.
The other material I have tested is a kaolin clay-based material called Surround (currently
registered). This material creates a barrier over the nuts and requires very good coverage. In
my experience, it is most effective on younger trees with a handgun. Initial tests indicate that
it might also help increase nut size, improve nut quality and result in earlier harvest maturity.
This and other University of California success stories can be viewed at our statewide
website at http://ucanr.org . Click on UC Delivers on the left side of the screen. My husk
fly article is under fruits and nuts.
PEACH TWIG BORER: APRICOTS
Peach twig borer larvae are the most significant “worm” pests of apricot fruits at or near
harvest time. The larvae feed at the stem end and may bore down to the pit. They are
chocolate brown with lighter colored bands between each segment. I am catching large
numbers in pheromone traps despite the cool weather. The biofix for Central Coast interior
valley locations (Hollister, Gilroy, Morgan Hill) was March 29. The spray window is
between 400 and 500 degree-days. The chart below lists estimated spray dates for several
locations as of April 28 utilizing CIMIS or UC IPM TouchTone temperature data. The actual
date may be somewhat earlier or later depending upon May weather. Some shorter residual
insecticides have not provided complete control of the May brood of peach twig borer larvae.
You may want to re-assess your control program at this time if that has been a problem.
Morgan Hill/Gilroy
Ausaymas/North San Benito County
Hollister
400 DD
500 DD
May 15
May 17
May 20
May 23
May 26
May 29
COOPERATIVE EXTENSION BUDGET MESSAGE:
The University of California Cooperative Extension will receive a very significant budget cut
if the currently proposed state budget is passed. I have attached an information sheet
discussing the implications for UCCE from UC ANR Vice-President Reg Gomes. For more
information, visit our website at http://ucanr.org and click on State Budget Update.
William (Bill) W. Coates
Farm Advisor, Fruit and Nut Crops
San Benito, Santa Cruz, Santa Cruz
and Monterey Counties
Univ. of Calif. Cooperative Extension
335 West Street
Hollister, CA 95023
(831)637-5346 phone
(831)637-7111 FAX
e-mail: bwwcoates@ucdavis.edu
web: http://cesanbenito.ucdavis.edu/
Mail: P.O. Box 1956
Hollister, CA 95024-1956
For those without internet access, call or write me and I will provide hard copies of any
information mentioned above. Reference to commercial products or trade names is with the
understanding that no discrimination is intended, and no endorsement by Cooperative
Extension is implied.
The University of California prohibits discrimination against or harassment of any person on the basis of race,
color, national origin, religion, sex, physical or mental disability, medical condition (cancer-related or genetic
characteristics), ancestry, marital status, age, sexual orientation, citizenship, or status as a covered veteran
(covered veterans are special disabled veterans, recently separated veterans, Vietnam era veterans, or any other
veterans who served on active duty during a war or in a campaign or expedition for which a campaign badge
has been authorized) in any of its programs or activities or with respect to any of its employment policies,
practices, or procedures.
University policy is intended to be consistent with the provisions of applicable State and Federal laws.
Inquiries regarding the University’s equal employment opportunity policies may be directed to the Affirmative
Action/Staff Personnel Services Director, University of California, Agriculture and Natural Resources, 300
Lakeside Drive, 6th Floor, Oakland, CA 94612-3550, (510) 987-0096.
Proposed Cuts to UC Agriculture and Natural Resources Programs
— What Do They Mean for Californians?
THE SITUATION
•¡ The University of California took significant budget cuts this year; even deeper cuts are proposed for
next year.
•¡ Unless the Legislature acts to reduce the cuts, UC Cooperative Extension (UCCE) will take a 30 percent
budget cut and UC state-funded research, a 20 percent cut.
THE CONSEQUENCES
If the Legislature approves these cuts to Cooperative Extension and research:
•¡ UC will need to close offices and facilities, begin layoffs, and eliminate core Cooperative Extension
and agricultural research programs.
•¡ The network of UCCE county-based advisors will be decimated.
•¡ UC research discoveries and innovations — advances that fuel economic growth, sustainable use of
agricultural and natural resources, better human health and nutrition — will slow or be lost.
•¡ We will no longer be able to respond to threats from bioterrorism, exotic pests and diseases, and
natural disasters.
WHO WILL BE AFFECTED?
Budget cuts of 30 percent for Cooperative Extension and 20 percent for UC research will have
consequences far beyond the elimination of programs and people and closing of offices and facilities.
These consequences will last far beyond today’s budget crises.
•¡ In the end, all Californians — whether they live in cities or rural areas, work on farms or in high tech,
are long-time residents or newly arrived — will feel the cuts.
•¡ So will the state’s economy, as UC programs are shutdown — programs that generate new ideas, technological
advances, and innovations that California agriculture and other businesses rely on to
compete globally.
Here are examples of how the proposed budget cuts to UC programs in Agriculture and Natural
Resources will impact Californians:
•¡ Economic Growth — Agriculture is one of California’s leading industries, contributing substantial
income and employment to the state’s economy. One of the most stable industries in the state, agriculture
is largely immune from the boom or bust cycles that other sectors have experienced in recent
years. Studies show that nearly half of the economic growth in California agriculture is directly attributable
to UC research and Cooperative Extension. Cuts to these programs will slow economic recovery
in California.
•¡ Public Service — A 30 percent cut to Cooperative Extension will require elimination of statewide and
local programs. No decisions have been made as to which ones, but everything will be on the table:
statewide programs, such as the Agricultural Issues Center, integrated pest management (IPM),
sustainable agriculture, water resources; nine research and extension centers; extension offices and
programs in every county.
•¡ Ripple Effects — Over 85 percent of the state dollars in agriculture and natural resources fund salaries
and benefits of people in the University who, in turn, generate outside funding for programs and
research. For each dollar of state funds lost to UC research programs in agriculture and natural
resources, an additional dollar leveraged by our scientists is lost to the California economy.
•¡ Crisis Response — In the past, UC has responded effectively to threats from exotic pests and diseases:
the glassy-winged sharpshooter and Pierce’s disease, red imported fire ants, sudden oak death,
medflies, etc. With the proposed cuts, our ability to respond to acts of bioterrorism, emerging diseases
and natural disasters will be lost.
01/03
TREE TOPICS
NEWSLETTER
APRIL, 2003
COOPERATIVE EXTENSION
U.S. DEPT. OF AGRICULTURE
UNIVERSITY OF CALIFORNIA
OAKLAND, CA 94612-3560
____________________________
Official Business
Penalty for Private Use, $300
COUNTY CODE = 35