Issue 14 -- July 03, 2001
Cornell Fruit Field Day
The fruit team at Cornell University is pleased to announce that it will
host a field day on August 15, 2001 from 8:00 am - 5:00 pm at the experimental
farms near Ithaca to view research and demonstration plantings involving
tree fruits and berries, and to learn about post-harvest and spray application
technologies for these crops. Attendees will have the opportunity to see
plantings of apples, peaches, blueberries, raspberries, strawberries,
pears, chestnuts, blackberries, kiwifruit, and other alternative fruit
crops, and to learn about experiments being conducted on them. The emphases
of the research at the Ithaca locations are low impact pest management,
understanding the below ground environment, variety testing, and post-harvest
physiology. Included will be a demonstration of three new sprayer types
for small trees and berry plantings. The field day will start at 8:00
am, lunch will be served at the beautiful Cornell Plantations, and transportation
will be provided to the Lansing orchard located at a spectacular setting
along Cayuga Lake. The cost for the event is $20.00. Attendees must pre-register
or make a reservation by August 1. Call 607-255-5439 or email mw45@ cornell.edu
to reserve your spot at the Cornell Fruit Field Day, or send a check made
out to Cornell University to Fruit Field Day, Dept. of Horticulture, Cornell
University, Ithaca, NY 14853.
Foliar Calcium Benefits in Apple
Jeremy Compton, North Jersey Tree Fruit Technician and Win Cowgill,
Agricultural Agent, Rutgers University
(Jon Clements comments in parentheses)
It is time to consider adding foliar calcium to your apple cover sprays.
Calcium-related disorders such as cork spot, bitter pit and senescent
(internal) breakdown are common in New Jersey (as well as in Massachusetts.)
These disorders cut into grower returns by making the affected fruit unmarketable.
(Calcium related disorders often show-up during long-term CA storage –
a bad situation given the added cost of storage.) Some cultivars, such
as Jonagold, Cortland, Enterprise (and Honeycrisp!) and most early season
varieties can be highly sensitive to calcium deficiencies in the fruit.
Correction of calcium deficiencies begins with maintaining adequate soil
calcium levels thorough regular liming with high calcium lime only. However,
soil-applied calcium does not easily translocate within the tree, and
many factors, such as nutrient imbalance, soil moisture, pH, crop load
and pruning may all effect how well the tree utilizes the calcium available
in the soil. The quickest and most effective short-term corrective treatment
for the control of calcium-related disorders is the implementation of
a foliar calcium spray program.
Calcium sprays have been a hot research topic over the past three decades.
Although major advancements have been made in the reduction of calcium
related disorders, no universal ‘cure’ has been found. The most
important aspect of a foliar calcium program is the total amount of calcium
that ends up in the orchard. Pennsylvania recommends 4 to 14 pounds of
total calcium per acre per season, while Massachusetts recommends between
21 and 22.5 pounds of actual calcium per season. The cooler climate of
the New England states allows them to apply such an intensive spray schedule
without any significant leaf burn. In work conducted at the Rutgers Snyder
Research Farm over the past 7 years on Enterprise, we have sprayed over
11 pounds of actual calcium per acre per season without any significant
leaf burn. Our standard recommendations in New Jersey are to apply 2-3
lb/100 gallons of CaCl2 per spray before August 1st and 3-5 lb/100 of
CaCl2 per spray after August 1st.
This will allow for sufficient absorption of calcium by the fruit with
minimal leaf burn on most cultivars. Research has shown that late season
foliar applications of calcium are more effective in reducing calcium-related
disorders than early season sprays, but total applied calcium by harvest
is the most significant factor. Reduced rates of CaCl2 should be applied
if there was no rain between applications, or if we are experiencing hot
and humid conditions. Care should be taken when applications are occurring
in temperatures above 80°F. Since foliar applications of calcium do
not translocate through the leaves readily, it is important to get thorough
spray coverage to allow for calcium to contact the fruit directly. Increased
water volume or the addition of a surfactant may provide better coverage
and increased absorption while reducing the chance of any leaf injury.
There are many calcium products promoted by industry as substitutes for
Calcium Chloride (CaCl2). How ever, extensive research and comparison
of these products has yet to show an advantage over Calcium because it
is one of the richest forms of calcium at the cheapest price. Calcium
nitrate, Ca(NO3)2 can be substituted for CaCl2 but only on trees that
do not contain low nitrogen levels as measured by leaf analysis. Vigorous
trees should not receive Calcium nitrate. Growers opting to use Ca(NO3)2
as their calcium source should be aware that Ca(NO3)2 does not contain
as much available calcium as CaCl2, so they should adjust their rates
accordingly. (3.2 to 5.3 pounds calcium nitrate per 100 gallons dilute.)
(For more information on calcium sprays, see F-119R, ‘Foliar Calcium
Sprays for Apples’ by Wes Autio and Bill Bramlage, It is available
on the UMass Fruit Advisor, http://www.umass.edu/fruitadvisor/)
Scab Susceptibility of 21 Cultivars at the HRC, Belchertown, MA
A planting that consists of 21 cultivars (5 replicates of each), many
of them new numbered varieties, were planted in 1999 at the UMASS Orchard
as part of a wide-scale study (NE183) to evaluate these cultivars for
disease susceptibility. On June 12, leaf scab was evaluated by counting
presence or absence of active scab lesions on 4 terminals per tree on
each of the 105 trees. Other diseases, such as cedar apple rust and powdery
mildew were noted, but incidence was too rare to warrant analysis. Several
cultivars had scab on 70% or more of the terminals (in descending order
from most severe): 'R. Macintosh', 'NJ 90', 'MN 1824', 'NJ 109', 'Hampshire',
'BC 8525-33', and 'Ambrosia'. These were significantly different from
8 of the cultivars that had very little scab (less than 1.5 %) and from
a 9th cultivar that had scab on 25 % of the terminals. These cultivars
were (in descending order from 25 %): 'CQR 12T50', 'NY 65707-19', 'BC
8526-50', 'NY 75907', 'CQR 10T17', 'Coop 25', 'NY 75907-72', 'Coop 39'
and 'Coop 29'. There was an intermediate group, some of which were significantly
different from the extremes of the other 2 groups, that ranged from 62%
scab to 30 %: 'Golden Delicious', 'Runkle', 'Pinova' 'Delblush', and 'Jubilee
Fuji'.
Later this year, fruit scab, flyspeck, sooty blotch, and summer rots will
be evaluated. This study is part of the NE 183 program.
Summer Diseases
Squash mounts of flyspeck fungal structures collected from host plants
in orchard borders across the state (except for the highest locations)
indicate that we are now in the middle of ascospore release. This is slightly
later than usual. We rarely see flyspeck on apples before July 20, and
this year we don't except to see any before the 25th or 30th.
Apple Maggot
Now's the time to swing into action with sticky spheres for monitoring
apple maggot flies (AMF). There's no better way of determining whether
you need an AMF spray than hanging some 3-inch red spheres on perimeter
apple trees.
Last year was an especially good one for highlighting the value of using
spheres. There were fewer AMF entering commercial orchards in 2000, and
there was less AMF damage to commercial fruit, than in any of the nearly
25 years we have been monitoring AMF in Massachusetts. Many growers needed
to spray only once to gain essentially complete control of AMF. But without
the presence of red spheres, there was no way to have known just how light
the AMF population was. So one or two extra sprays could have been applied
needlessly.
If you already have spheres on hand from last year and need to clean
them before applying sticky, there's a very easy way of cleaning them
that works well. Simply cut a 2 x 2 inch piece of plastic from a milk
carton, or similar container, cutting a slight crescent-shaped curve at
one end. Run the curved end 3-4 times across the sphere surface. If the
spheres are placed in a warm and sunny place before cleaning, the old
sticky is soft and very easily removed. It takes only a few seconds to
clean a sphere of most of the old sticky and all of last years insects.
Applying new sticky is just as easy. The type of sticky that works best
is Tangletrap. A small putty knife serves well as an applicator. Getting
the right amount of sticky on the sphere is a bit tricky. There should
be enough to hold an alighting AMF but not so much that it will run down
the side of the sphere on a warm day and drop off from the bottom in a
blob. Nothing worse for a picker than to handle an apple or foliage covered
with sticky applied too generously to a monitoring sphere.
If you don't already have red spheres, they can be purchased at Orchard
Equipment and Supply in Conway, or from Great Lakes IPM (517- 268-5693)
or Gemplers (800-383-8473), among other sources.
Proper positioning of the spheres is the most important step in the process.
First, select perimeter-row trees that are prone to AMF injury. Over the
past 3 years, we have studied intensively a dozen or so cultivars for
susceptibility to AMF. All early-ripening cultivars (except Paula Red)
are susceptible. So is Gala. Most other cultivars are not as susceptible.
In fact, most strains of McIntosh and Cortland rank low in susceptibility.
The following is a guideline for finding the best position within a tree
canopy for placing a sphere. Look for a place on the tree that has a lot
of fruit in the outer third of the canopy at head height. Try to imagine
the red sphere positioned at the center of a sphere of apples. AMF spend
lots of time in areas of trees having lots of apples. They have a high
chance of being caught on a sphere surrounded by apples. AMF spend little
time in areas of trees with fewer apples. Remove all apples and foliage
within 6 inches of the sphere to provide an unobstructed view of the sphere.
Before walking away, make sure that the sphere isn't hanging too far out
on the edge (devoid of any apples directly beneath) or too far inside
the canopy (where it may be too dark to be seen readily). No odor bait
is needed so long as spheres are hung on trees of susceptible cultivars.
The odor of the fruit itself attracts AMF to the tree.
If you catch an average of 2 or more AMF per trap, you have reached the
threshold and it's time to spray.
Mites
Red mites remain very low in nearly all monitored orchards. There is
only an occasional block showing signs of possible future trouble. Such
blocks received only a single oil application and no other miticide. Overall,
things continue to look very good on the mite front.
Leafminers
Some second-generation sap feeders are starting to appear. But as indicated
in previous issues of Healthy Fruit, few blocks require LM attention this
year. In fact, in our 48 monitored IPM blocks distributed across the state,
none showed LM as exceeding a threshold of 13 first-generation mines per
100 leaves.
Japanese Beetles
The first adults have been seen. Last year they were a major league problem
in some orchards, though only rarely on bearing apple trees. The simplest
and cheapest way of handling this potentially very damaging pest is to
treat infested trees or plants with Sevin. Guthion and Imidan are not
as effective.
Stink Bugs
Stink bugs have been seen recently feeding on peaches. If uncontrolled,
they can cause severe dimpling and cat-facing of developing fruit. Numerous
studies have shown that SBs are eespecially numerous in orchards where
the ground cover gets too high before mowing. Periodic mowing denies SBs
the availability of flowering understory plants (especially mullein),
which attract SBs into orchards. Just before mowing an understory containing
lots of plants in bloom, it's best to spray peaches with a material that
can control SBs. A synthetic pyrethroid such as Ambush, Asuna or Pounce
at 2 ounces/100 gal has done an effective job of controlling SB on peaches
in the past.
|
