gallons at PF-5mm. (See above caution).

Accel is a newer material that works as a mild thinner
but has the ability to increase fruit size over and above the
thinning response. It is valuable for use on small fruited
cultivars like Empire. (See Dr. Ed Stover comments
below). It is best applied PF to 8mm and used at the
maximum rate which is 30 grams/A. It is best used in
combination with other materials for effective thinning.
Sevin or Vydate are our two choices for combination.
Caution:Do not use on any trees treated with NAA or
NAD this year, they are not compatible. Avoid drift on
threes that have been treated with either NAA or NAD.

Sevin is a carbamate insecticide that is a standard
thinner for apples. Only Sevin XLR-Plus should be used.
It is safer on bees and has been reported to have less
toxicity to mite predators. It has the same concentration of
active ingredient as Sevin 50W and thins the same way.
Sevin is a mild thinner at the full rate 1quart/acre. It can
be used at PF till 20 mm and is best used in combination
with other thinners (NAA or Accel) with most varieties.
When used alone it may underthin some cultivars in NJ.
(Do not use Vydate in combination with Sevin).

Vydate Lis a carbamate insecticide that works the
same way as Sevin. It has been a state label in NJ since
1996 based on our research trials in North Jersey. It too is
a mild thinner like Sevin and should be used in
combination with another thinner for best results (NAA or
Accel). At 1-2 pints per 100 gallons it should be applied
dilute between PF/5MM and 20MM. Up to two
applications can be made per season. Vydate may be less
toxic to mite predators than Sevin and at the 1-2 pint
/100 rate may have activity on spotted tentiform leafminor
and white apple leafhopper.

Dilute Vs. Concentrate Spraying

Thinning Chemicals are effective if applied dilute and
at 300 gallons per acre. Concentrate sprays may be
applied with reasonable success, however, it is suggested
that no less than 100 gallons of spray per acre be used.
At 3x, the amount of chemical used per 100 gallons is
three times the concentration listed on the label but the
spray rate is only 100 gallons per acre.

Defruiting Young Apple Trees

Sometimes 2- and 3-year-old apple trees set a heavy
crop of fruit. This is undesirable because it restricts
growth and delays good production in the future. Also,
the leader bends over and the tree may develop a poor
framework.
A mixture of 2 pounds of Sevin 50WP plus 15 ppm
NAA plus 1 pint of 70 second superior oil per 100
gallons of water applied at petal fall to 14 days after full
bloom will remove most of the fruit. This spray will not

remove all of the apples.
about June 15.

Hand remove those remaining

Summaries and Comments from Dr. Ed
Stover of the Cornell Univ. Hudson
Valley Lab

Time of Thinning [!]In general, earlier thinning will give larger fruit size at a comparable cropload. [!]Use of multiple thinning treatments may give better control of cropping in difficult to thin blocks, with higher profitability and probably better return bloom. [!]NAA/Sevin on "Empire': 1) has been remarkably consistent from petal fall through 15 mm king fruit diameter (KFD), but usually yields better fruit size relative to cropload comparable to the best Accel/Seven treatments; 3) usually breaks up clusters more effectively than Accel/Sevin. Use of Accel [!]Accel/ Sevin in combination gave a much more consistent response than Accel alone, still more variable than NAA/Sevin. [!]No benefit to using Accel unless you get significant enhancement of fruit size. [!]In 'Empire' best fruit size enhancement from Accel around 10 mm KFD, some response at 5- 15 mm KFD but only thins from earlier treatments. [!]With 'Empire', in most cases, Accel/Sevin gives substantially greater crop value than NAA/Sevin. [!]Excellent results in 'Empire' from using Accel or Accel/Sevin at 10 mm KFD after earlier thinning treatment: resulted in similar fruit size advantage relative to cropload as Accel/Sevin alone. [!]We had poor results with Accel or Accel/Sevin in 'Delicious' in 2 of 3 years of trials; other researchers (especially in Mid- Atlantic) report better response with lower rates than we have tried. Note: Accel/Sevin has not provided good results in northern NJ as well on Red Delicious, it has provided good results on Macintosh.

78

1998 New Jersey Commercial Tree Fruit Production Guide