Benlate, Topsin-M, and Cyprex are present in all areas of
New Jersey. Therefore, these fungicides should not be
used unless scab isolates from your orchard have been
tested for fungicide resistance.
With the heavy dew and cooler night time
temperatures from mid-August through harvest, scab can
become reactivated. Late fruit infections may not be
visible to the naked eye, but these infections can develop
into tiny fruit infections which develop in storage.

Bitter Rot. The fungus causing this disease,
Colletotrichum gloeosporidides, overwinters in cankers
on the twigs, branches, fruit spurs, or in mummified fruit
on the tree, or on the ground. The spores are splashed
from the infected tissue during periods of rain and
infections occur to uninjured fruit beginning in mid-June.
Infections can continue to occur into October. Fruit
infections are firm and they appear flattened or sunken.
Control consists of using fungicides with longer
residual activity and spraying orchards on a regular
schedule. Proper pruning to remove dead wood also
assists in control.

Black Rot. The fungus Botryosphaeria obtusa
overwinters in cankers and mummified fruit on the tree. It
is responsible for frog-eye leaf spot and black rot on
apples. The spores wash and splash from twigs and
mummies to foliage and fruit below. Therefore, dead
twigs, especially fireblight twigs, should be removed
during the pruning operation. Ferbam and captan have
shown promise as protectants against black rot infection.

Blister Spot.This disease is caused by the bacterial
pathogen Pseudomona syringae pv. Papulans. It is
troublesome on Mutsu and Magnolia varieties during
years when excessive rainfall occurs during the early part
of the growing season. It may also occur on other
varieties in lesser quantities.
Symptoms consist of purplish black lesions, 4-5 mm
in diameter, that appear at fruit lenticels. Disease if first
noticeable at 2-3 months after petal fall, at which time
only small, green raised blisters are visible. Theses
blisters eventually expand and darken with age.
Control consists of using copper containing
fungicides (1 lb ai/100 gal) beginning at FIRST COVER.
Repeat sprays at SECOND and THIRD COVER.
Streptomycin is as effective as copper-containing
fungicides but Terramycin is ineffective in control.

Brooks Spot. This disease, caused by
Mycosphaerella pomi, is most troublesome on Rome and
Stayman, but it can be troublesome on other apple
varieties. Fruit symptoms appear 8 to 12 weeks after the
infection occurred as slightly sunken, greenish lesions
which occur associated with the lenticels of the fruit. At
harvest the spots are dark purple in color. Foliar lesions
appear in August as small purplish flecks around the leaf
stomata.
Benlate is highly effective in control. Other fungicides
with long residual activity may provide good control.

Cedar Apple Rust. Rust infections occur between
pink and third cover spray. Infections which occur early
can occur on the fruit and leaves. Infections which occur
after first cover infect only the leaves. Materials which are
effective against rust include: Thiram, Ziram, Ferbam,
Bayleton, Funginex, Nova and Rubigan.

Collar Rot. Collar rot, caused by various species of
the Phytophthorafungus, can be a serious problem with
MM106 and MM104 rootstocks. It also causes some loss
of trees on other rootstocks. The disease is most
troublesome in orchards with poor internal drainage or in
areas where water lays. Control consists of using more
tolerant rootstocks and in improving drainage. The
disease can be brought into the orchard with infected trees,
so care should be used when purchasing trees.
Ridomil 2E, Ridomil Gold, and Aliette are labeled
for control in bearing and nonbearing blocks and are
effective when used according to label directions. Please
refer to the section on Fungicides and Bactericidesfor
details on using these products.
Copper-containing fungicides and maneb have
provided some measure of control when applied as a
drenching spray to the trunk. Use 4 pounds of maneb or 2
pounds of actual copper in 100 gallons of spray and apply
1 gallon of spray per tree in late March to mid-April and
again late September to mid-October.

Nectria Canker. This disease, also called European
canker, can be a problem on varieties with enlarged
terminal fruiting spurs, such as Rome Beauty and
Jerseyred. Infections occur in the fall as leaves are
dropping. The symptoms of infection occur in June when
the terminals begin to die. The disease can be confused
with fire blight except all infections arise from the swollen
terminal fruiting spur with European canker.

Fire Blight. The following practices should be
employed to reduce loss from this disease.
[!]Pruning.The most recent theory on
control suggests that infected shoots should not be
cut out until the terminals harden-off. After terminals
harden-off and before leaf fall, prune twigs 4-6 inches
below any visible evidence of the disease. If the
disease progresses into the main trunk, the trunk
should be cut back 4-6 inches below any visible
symptoms.
Pruning tools should be disinfected by wiping
them with a cloth saturated with 70 percent isopropyl
(rubbing) alcohol or sodium hypochlorite (Household
bleach) 1:10 dilution with water. Tools may also be
dipped in these solutions. Tools dipped in bleach should
be washed in clean water at the end of the day to prevent
corrosion of the metal parts.

[!]Prebloom Sprays. In blocks where fire blight is anticipated, growers may wish to apply a copper spray at HALF-INCH GREEN. This spray will kill the bacteria present on the plant surface and may reduce later infections. It will also help for scab control

114

1998 New Jersey Commercial Tree Fruit Production Guide