Northern Michigan FruitNet 2009
Weekly Update
NW Michigan Horticultural Research Station
| Nikki Rothwell District Horticulturist |
Erin Lizotte District Fruit IPM/IFP Agent |
Bill Klein Farm Mgr, NWMHRS |
| Duke Elsner Agricultural & Regional Viticulture Agent |
May 19, 2009
GROWING DEGREE DAY ACCUMULATIONS AS OF May 18th AT THE NWMHRS
Year |
2009 |
2008 |
2007 |
2006 |
2005 |
2004 |
19yr. Avg. |
GDD42 |
381 |
394 |
495 |
548 |
430 |
379 |
422.5 |
GDD50 |
162 |
177 |
230 |
256 |
194 |
166 |
198.6 |
Growth Stages at NWMHRS (5/18/09- 4:00
p.m.)
Apple: McIntosh & Yellow Delicious – 80% King bloom
Gala & Red Delicious– 50% King bloom
Pear:
Sweet Cherry: Hedelfingen: Late petal fall
Napoleon: Late petal fall
Gold: Early petal fall
Tart Cherry: Early petal fall
Balaton: Early petal fall
Apricot: Early shuck split
Grapes: Bud swell
Weather
We continue
to be cool and dry in the north. Last
Wednesday and Thursday, we received just under a ½” of rain, but the ground is
still dry. On Saturday we had about 10 drops of rain – just enough to kick off
a few infection periods. We have
accumulated 381 GDD base 42 and 162 base 50. We are behind the 19-year average, which is 422.5 GDD base 42 and 198.6
GDD base 50. We had some overnight cold
temperatures during the evening of May 17, and the low temperature in the area
was ~ 28°F at the Elk Rapids MAWN site.
Crop Report
Pears are
at full bloom to early petal fall. All
varieties of apples are at king bloom: 50-80%. Montmorency and Balatons are at early petal fall and sweets are at late
petal fall at the NW Station. As we move
north, cherries are in full bloom. Plums
are at early petal fall and apricots are at early shuck split. We have seen a bit of frost damage in apples
and sweets. However, bee activity is the
main issue now, as conditions have been extremely windy and on the cold side.
Apple - Spotted tentiform leafminer flight has slowed at the station with
catches down to 10 adults per trap, compared with 75 per trap last week. Eastern
tent caterpillar webbing is visible throughout the region at higher levels
than commonly seen. Under high pressure
Eastern tent caterpillar can be a pest in apple and cherry and may require control
this season. There are many management
options for Eastern tent caterpillar – anything that works on caterpillars will
work. Pyrethroids would be economical
and effective. Early last week the first
report of plum curculio in pyramid
traps came out of a
As we move
through the week, rain is again in the forecast and based on a biofix of 4/25
(Macintosh green tip), apple tissue should be kept covered with ascospores
maturing quickly and an average of 40% spore discharge forecasted by
Friday. Based on forecast data, we have
had a couple of false scab infection
alarms over the past weeks; scab infection periods were predicted but never
occurred due to cooler temperatures. Temperatures
will not be a limiting factor in apple scab infection this week, and tissue
should be kept covered. As we see king
bloom opening in the
Cherry - In cherry we are catching green fruitworm in the Station trap
line, with an average of 10 moths per trap this week, down from 22 last
week. We also caught the first American
plum borer this week (10 moths/trap). Early last week the first report of plum
curculio in pyramid traps came out of Leelanau county despite the cool
overnight temperatures the region has been experiencing. With warmer overnight temperatures forecasted
for this week, we expect to see increased plum curculio activity in the coming
days. As leaf tissue begins to emerge,
growers should keep an eye on the cherry leaf spot infection model. Remember, leaves must be unfolded, exposing
the stomata for leaf spot infections to occur.
Grape – We have yet to catch potato leafhopper or grape berry moth in trap lines around
the region. Climbing cutworm damage has been reported from one area vineyard,
and we continue to see a few grape
leafhopper on sticky traps. For an
updated version of the pest report during the week call (231) 947-3063.
SPECIAL LOCAL NEED REGISTRATION GRANTED ON INDAR FOR AMERICAN
BROWN ROT CONTROL
Dr. George Sundin,
Dept of Plant Pathology, MSU
A Special Local Need [EPA 24(c)] registration has been
granted for the use of increased rates of Indar 2F for brown rot control. The
basis for this request was from our observations that populations of the
American brown rot fungus (Monilinia fructicola) are shifting in Michigan towards decreased sensitivity to sterol
inhibitor fungicides (see March 31 Fruit CAT Alert article). Note: this special registration only applies to
Indar 2F.
Fungal sensitivity/resistance to sterol inhibitor
fungicides acts in a quantitative manner, meaning that a fungus with a
decreased sensitivity to one rate can be controlled by a higher rate of the
same fungicide. Results from an orchard survey conducted by Erin Lizotte
indicated that there was clear shifting in the American brown rot population,
and that some orchards harbored American brown rot isolates that were close to
the resistance threshold. The use of
higher rates of a sterol inhibitor fungicide acts as a hedge against resistance
development. The higher rates are effective against fungal isolates that show
decreased sensitivity; controlling these isolates then decreases the chance of
further shifting to resistance.
Currently, the use of Indar 2F at the original
label rate of 6 fl. oz. per acre should provide excellent control of American
brown rot in most orchards. However, as a hedge against further shifting of the
American brown rot population in most orchards, my suggestion is to use a rate
of 8 fl. oz. per acre in 2009 for control of fruit infections. Growers whose
American brown rot orchard populations are closer to the resistance threshold
should consider using a 9-10 fl. oz. per acre rate. It is essential, especially this year after
the heavy American brown rot infections observed in 2008, that fungicide
coverage is excellent. This will ensure a uniform exposure of the fungus to the
higher rate of fungicide.
The 24(c) registration allows as high a rate as 12
fl. oz. per acre. A maximum of 48 fl. oz. per acre is allowed per season, i.e.,
no more than eight applications at 6 fl. oz. per acre or four applications at
12 fl. oz. per acre. Do not graze livestock in treated areas or feed cover
crops grown in treated areas to livestock. Do not apply Indar 2F through any
type of irrigation system. Always read
and follow the label carefully when applying any pesticide.
CHERRY LEAF SPOT
Erin
Lizotte, IFP/IPM District Educator, MSU-E
Cherry leaf
spot (CLS) is arguably the most damaging fungal pathogen of tart cherry. CLS primarily infects foliage and reduces the
photosynthetic ability of a tree through tissue degradation and early
defoliation. When significant
defoliation occurs before harvest, fruit may be soft and immature, have low
soluble solids and ripen unevenly. For a
point of reference, at least two leaves are needed to effectively ripen each
cherry and defoliation that reduces leaf numbers to below that threshold can
cause damage to the current year’s crop. Blossom production may also be reduced in subsequent years and following
severe defoliation, trees are more susceptible to winter injury because of the
loss of stored carbohydrates in the roots.
CLS
overwinters in fallen leaves on the orchard floor and produces apothecia
(sexual spore-bearing structures) in the spring. Ascospore (sexual spore) dispersal occurs
during the drying period that follows a wetting event and temperatures between
60-85°F. Infection occurs through the
leaf stomata, which remain susceptible throughout the growing season. The primary infection period may last 2-6
weeks depending on conditions. Following
infection, acervuli (asexual spore-bearing structures) develop on the underside
of the leaf and produce a visible mass of asexual spores called conidia. Spores are dispersed from leaf to leaf by
wind or rain and this secondary infection cycle can be repeated several times
within a season, depending on conditions. All commercial cherry cultivars are susceptible to CLS. CLS is resistant to sterol inhibitor
fungicides (Indar, Elite, Orbit) in all the major fruit producing areas of
The table
below lists season long recommendations for management; we are currently
heading into the timing for a petal fall application in northern
TAILORING FIRE BLIGHT PREDICTIONS TO
YOUR SITE: THE FIRE BLIGHT INTERACTIVE PREDICTOR
Originally
published in the Fruit Crop Advisory Team Alert
Bill Shane,
District Extension Fruit Educator
Tracy
Aichele, Enviroweather
A
new feature for predicting fire blight disease of apples blossoms has been
added to the
The underlying model for blossom blight in the Fire Blight Interactive
Predictor model is the same as is used in the Fire Blight Assist Chart that has
been on Enviroweather for several years. The Fire Blight Interactive Predictor
version provides more versatility and allows the user to gain a better
understanding of conditions that favor fire blight epidemics.
The Fire Blight Interactive Predictor is based on Maryblyt, a popular computer
program developed by Dr. Paul Steiner and Mr. Gary Lightner, Department of
Botany at the
·
Open blossoms (B).
·
Sufficient warm temperatures
over the past several days to increase fire blight bacterial growth on blossoms
(H).
·
A wetting event such as
rain, dew, fog or spraying (W).
·
Average daily
temperature of at least 60°F (T).
The fire
blight risk for each day during bloom is given as low, moderate, high, or
infection when one, two, three, or four of these conditions are met. For many
users, this will be all they need to know to make spray decisions. Bactericide
applications are definitely needed for predicted infections and possibly for
high fire blight risk ratings. The Fire Blight Interactive Predictor keeps
track of multiple infection events and calculates when symptoms are expected to
show in the orchard. The Predictor is useful for summarizing fire blight
conditions for past seasons, which helps in comparing years and unraveling
reasons for disease outbreaks.
A feature in the module that will be prized by advanced users is the ability to
temporarily change rainfall, temperature, bloom start and end dates,
bactericide spray, and trauma events like hail or high winds to better match
local conditions or to try “what if” scenarios.
For example, if the user suspects that the maximum temperature may or has been
higher than predicted or recorded for a nearby Michigan State University MAWN
weather station, the higher temperature can be substituted to see the resultant
prediction. The Fire Blight Interactive Predictor can be used to work backwards
to discover when the infection took place that was responsible for unexpected
symptoms showing up in the field.
In some respects the Fire Blight Interactive Predictor is a step backwards
closer to the original Maryblyt model by Steiner and Lightner still used by
some growers and consultants in its original PC DOS format, the only version
released and no longer available. The Predictor uses the essence of Maryblyt
model in the MSU Enviroweather network to deliver real-time fire blight
predictions to busy people.
REMEMBER TO CONTROL ROSY APPLE APHID
EARLY!
Erin
Lizotte, IFP/IPM Educator, MSU-E
The
following has been modified from apples.msu.edu
Rosy apple
aphid (RAA) feeding curls leaves, deforms shoots, and stunts and distorts
fruit. We can have up to three generations of RAA in apple in
Treatments
for infestations must be made early before the aphids are protected inside
curled leaves. Chemistries rated as
excellent against rosy apple aphid include Diazinon, Superior Oil, Lorsban 4
EC, Esteem 35 WP, Actara 25 WG, Assail, and Calypso. If using Esteem, applications must be made
before egg hatch as there is no activity against adults. At this early application timing, be sure to
check pesticide labels for bee toxicity if pollinators are in the orchards
(Actara is highly toxic to bees). Also
keep in mind that foliar Lorsban applications may only be made prebloom and
that 70 sec. Superior Oil should only be applied between green tip and pre-pink
to prevent plant injury. Always read and
follow pesticide labels carefully before use.
Clarification
of Lorsban rules for apple:
¨
Lorsban
75WDG
o
Up
to two applications per year
o
Cannot
exceed 2lb ai/acre (this amount includes trunk sprays!)
o
Only
two of three of above options
¨
Lorsban 4E and Dow Advanced label
(new liquid formulation)
o
Can
only be used pre-bloom in apple
o
Can
also do a trunk spray
EASTERN TENT CATERPILLAR OUTBREAK
Ric Bessin,
Duke Elsner, Agriculture Agent,
Nikki Rothwell, District Horticulturist
The eastern tent caterpillar, Malacosoma americanum, is a native pest
in
The eastern tent caterpillar overwinters as an
egg within an egg mass of 150 to 400 eggs. These masses are covered with a
shiny, black varnish-like material and encircle branches that are about
pencil-size or smaller in diameter. The
caterpillars hatch about the time the buds begin to open, usually in early late April to early May in NW
Michigan. These insects are social; caterpillars from
one egg mass stay together and spin a silken tent in a crotch of a tree
although caterpillars from two or more egg masses may unite to form one large
colony. Caterpillars emerge to feed on
foliage in the early morning, evening, or at night when it is not too cold, but
remain within the tent during the heat of the day or rainy weather.
The larvae are black, hairy with a white stripe
down the back, brown and yellow lines along the sides, and a row of oval blue
spots on the sides. As the larvae continue to feed, they increase the size of
their nest until it is a foot or more in length. In 4 to 6 weeks the caterpillars reach 2 to
2-1/2 inches in size, and they begin to wander away from the nest in search of
protected areas to spin a cocoon. The adult moth emerges from the cocoon
about three weeks later. The moth is reddish-brown with two pale stripes
running diagonally across each forewing. Moths mate and females begin to lay
eggs on small branches, and the eggs will not hatch until next spring. There is
one generation per year.
If possible, growers should remove and destroy the
egg masses from fruit trees during winter as this tactic will greatly reduce
the problem in the spring. In the early spring, small tents can be removed and
destroyed by hand, and larger tents may be pruned out and destroyed. Duke
Elsner says to be sure to wear gloves as the hairs of the caterpillars can sometimes cause skin
irritation. Burning the tents out with a torch is not
recommended since this control tactic can easily damage the tree.
Natural enemies play an important role in reducing eastern
tent caterpillar numbers in most years. Caterpillars are frequently parasitized
by various braconid, ichneumonid, and chalcid wasps. Several predators and a
few diseases also help to regulate populations. These natural enemies can help
account for the fluctuating populations from year to year.
Unfortunately, insecticides are generally ineffective against mature
larvae. Therefore, if growers need to
use chemical controls in a particularly bad infestation in an orchard, they
should target young caterpillars. Growers should spray the foliage as
caterpillars leave the nest to feed and they would come into contact with the
insecticide. Larvae within the tents are
protected beneath the webbing and are more difficult to kill with an insecticide.
Spraying nests will be not be effective if the insecticide needs to be ingested
as they do not feed within the nest. Young larvae can be killed by applying an insecticide containing Bacillus thuringiensis, such as
Dipel. Other insecticides that are
labeled against Lepidoptera (caterpillars) should be effective at controlling
eastern tent caterpillars (Assail, SpinTor, pyrethroids, organophosphates, or
many others). Please call the NWMHRS if
you need help controlling these pests (231-946-1510).
MDA GAP AUDIT REQUEST FORM
Following is
the Good Agricultural Practices and Good
Handling Practices Audit Request Form for your use. For questions or to schedule a GAP/GHP
audit, call the
Insect and disease predictive information is available at:
http://www.enviroweather.msu.edu/home.asp
http://www.agweather.geo.msu.edu/agwx/forecasts/fcst.asp?fileid=fous46ktvc
http://www.cherries.msu.edu/
Fruit CAT Alert Reports
http://www.ipmnews.msu.edu/fruit/
This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm
ACTUAL
AND PREDICTED DEGREE-DAY
ACCUMULATIONS
SINCE MARCH 1, 2009
Please send any comments or suggestions regarding this site
to:
Bill Klein, kleinw@msu.edu
Last Revised: 5-19-09
