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Nitrogen (N)
New plantings
- If prepared properly, little N is needed the year of
growth.
Apply 0.6-1 ounce N per tree at bud break and again 4 weeks later.
Optimal levels
Leaf analysis (heavy crop will increase N by
0.2-0.3%)
- Hard cultivars -- 2.2-2.4%.
- Soft cultivars -- 1.8-2.2%.
Growth
- Nonbearing years -- 0.5-2 feet of growth.
- Bearing years -- 8-15 inches of growth.
Application
- If the percent N in leaves is greater than optimum,
decrease N application by 10% for each 0.1% leaf N is
above optimum.
- If the percent N in leaves is less than optimum,
increase N application by 10% for each 0.1% leaf N is
below optimum.
- For possible set improvement, apply urea (spray grade
with less than 0.25% biuret) at tight cluster to pink at
a rate of 3 lbs/100 gal and again at petal fall to seven
days after petal fall at a rate of 5 lbs/100 gal.
Potassium (K)
New
plantings
- Generally K is required only on bearing trees, except
for newly cleared land or on particularly sandy or
gravelly soil.
Optimal levels
Leaf analysis (heavy crop will have 0.4% lower)
- All cultivars -- 1.2-1.8%.
Application
- Deficient K -- 120-180 lbs K2O/acre
(200-300 lbs muriate of potash -- KCl).
- Optimum K -- 60-90 lbs K2O/acre
(100-150 lbs muriate of potash -- KCl).
- Excess K -- discontinue for a year.
Magnesium (Mg)
Optimal
levels
Leaf analysis
All cultivars -- 0.35-0.50%.
Application
- Deficient Mg -- use dolomitic limestone plus 15 lbs
Epson salts/100 gal. in petal fall, first cover, and
second cover sprays (avoid high temperatures or slow
drying).
- Optimum Mg -- continue present program.
Boron (B)
Optimal
levels
Leaf analysis
- All cultivars -- 35-50 ppm.
Application
- General program -- 1-2 lbs B/acre/year to the soil or
1 lb solubor/100 gal in first and third cover sprays (do
not apply later than 30 days after petal fall)
- Less than 25 ppm B 1.7 lbs solubor/100 gal in fall
plus 1 lb solubor/100 gal prebloom or 1 lb solubor/100
gal prebloom, first, and third covers or 1 lb solubor/100
gal prebloom plus 2-3 lbs B on the soil
- 25 to 34 ppm B continue present program plus 1 lb
solubor/100 gal at tight cluster or petal fall 35 to 50
ppm B continue present program
- More than 50 ppm B discontinue application for one
year
- Foliar applications in the fall (postharvest before
leaf drop) may improve flower development, pollination,
and set. Spring applications (first and second cover) may
improve recovery from cold damage.
Manganese (Mn)
Optimal
levels
Leaf analysis
- All cultivars -- 35-135 ppm.
Application
- Deficient Mn 4 lbs manganese sulfate/100 gal in the
first cover spray, or 3 sprays of a Mn-containing
fungicide.
Zinc (Zn)
Optimal
levels
Leaf analysis
- All cultivars -- 25-50 ppm.
Application
- Deficient Zn -- 1 lb or 1 quart zinc chelate
(EDTA)/100 gal at tight cluster and in the second cover
spray.
Copper (Cu)
Optimal
levels
Leaf analysis
- All cultivars -- 7-12 ppm.
Application
- Deficient Cu -- Bordeaux mix or copper sulfate (2 lbs/100 gal)
at green tip to 1/4-inch green.
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Issued by University of Massachusetts
Extension, Robert G. Helgesen, Director, in furtherance of
the acts of May 8 and June 30, 1914. University of
Massachusetts Extension offers equal opportunity in programs
and employment.
F-124:4/97-500
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