most frequently on the fruit and to the generally higher
wetness and humidity which occurs at the stem end of the
fruit.
Benlate/Topsin M (0.5 lb/100 gal), when applied at
petal fall, has resulted in "burn out" of many of the
overwintering lesions on the twigs. Thus, disease
pressure can be measurably reduced as a result of a lower
inoculum level. Fruit infections are most common from
shuck-split through third cover. Foliar sprays are effective
in protecting the fruit from infection, and a single
fungicide spray applied around first cover will provide
reasonably good control of twig infections in non-bearing
blocks.
The disease is troublesome in commercial blocks
when the trees did not receive a regular spray program in
the preceding year. This occurs when the block was
"frozen-out" the previous year and when a new block is
first coming into production. The disease can be
troublesome during periods of drought, since only 3 hours
of 100% RH is necessary for sporulation to occur.
Where the disease is troublesome, use half rates of
Benlate or Topsin M in combination with Sulfur or
Captan. Bravo is also a very effective material and has
good retention capabilities. Apply sprays from shuck-split
through third cover.

Sour Rot. The yeast Geotrichum candidum causes
this Sour Rot. The disease may occur in the orchard
during years when temperatures are abnormally high but
is far more damaging in the postharvest period. Affected
fruit exhibit a moderately firm rot on green fruit and the
skin does not slip readily. The rot on ripe fruit is very
soft and is quite watery in the later stages. A cheese-like
scum can be observed within the watery fruit and when
the juice dries on the surface.
Benlate and sulfur provide poor control in the
orchard, while captan and maneb provide fair control. The
use of chlorine in the hydrocooler water and in dump
tanks is the only effective control of the postharvest phase.

Stem Pitting.This virus disease becomes
established in a block as a result of planting infected
nursery stock or by planting healthy nursery stock in
infested soils. Since the virus responsible is transmitted
by nematodes, preplant nematicide treatments are
mandatory for control. Additional postplant nematicide
treatments will probably be needed every 2 years to reduce
possible spread. See the section "Nematode Control" for
recommendations.
The probability of introducing the virus into new
blocks with planting stock has been greatly reduced in the
last couple of years since nursery trees from areas known
to have the virus are grown in fumigated soil. Growers
should select trees that were grown in fumigated soil or
from areas not known to have this problem.
Dandelion, dock, and other broadleaf weeds serve as
hosts for the stem-pitting virus (TomRSV). Thus, to
prevent spread within the orchard, a concerted effort to
control broadleaf weeds and nematodes is needed.
Trees that are infected prior to planting will begin to
decline during the third growing season. Trees that

Rusty Spot.. The fungus which causes this disease is
believed to be the apple powdery mildew pathogen,
Podosphaerea leucotricha. Consequently, the disease can
be anticipated in blocks adjacent to mildew susceptible
apple blocks. Partial control can be secured by planting
less susceptible peach varieties in such sites.
Fruit infections can occur throughout the growing
season, but are most common at shuck-split and shuck-
off. Fruit not protected at these critical times may become
100% infected, even if a good spray program is employed
during the remainder of the year. The varieties most
susceptible to the disease are Rio-Oso-Gem, Jefferson,
Jerseyqueen, Biscoe, Loring, Early Loring, Redskin,
Jerseyglo, and Garnet Beauty.
Since it is a powdery mildew disease, dry weather
favors sporulation and spread of the mildew spores.
Periods of heavy or frequent rainfall are less favorable.
Also, moderate winters favor overwintering of the fungus
on apple, thus providing higher inoculum levels for rusty
spot in neighboring peach blocks.
Nova is considered the best material for disease
control, with Funginex providing some activity as well.

Scab.The fungus Cladosporium carpophilumcauses
peach Scab. It is very common on homeowner-produced
fruit and less common on commercially produced fruit.
The disease over-winters in twig cankers produced on
current season's twigs. Spores are released around shuck
split and for the remainder of the season.
The infection process begins each year from spores
produced in cankers formed on last year's growth. The
spores are not readily released into the air until they
become wetted. The period between infection and visual
appearance of the disease on the fruit is very long, from 40
to 70 days. Because of the long period between infection
and visual symptoms of the disease, early maturing
varieties may be harvested before the fruit spots are visible
to the naked eye. Infections can occur on the fruit, green
twigs, and leaves. Infections occur most readily at
temperatures between 65 and 75F when rainfall is
abundant. Infections can occur as low as 40-45F and as
high as 90-95F.
Cankers formed on current season twigs are light
brown, diffuse, small (1/16 to 1/8 inches in diameter)
initially, and later increase in size, becoming circular in
outline and turning a darker brown color. A slightly
raised bark callus surrounds the margin of the lesion. In
the spring, velvety-textured olive-colored spots appear
within the lesion.
On the fruit, the tiny spots appear around third cover
(early July in southern counties) when the fruit are about
one-half their final size. The spots develop quickly into
very dark, olive-colored, circular spots. Later the spots
appear almost black in color. The spots do not "break"
the skin as do the fruit spots caused by bacterial spot.
However, the skin frequently cracks open in the areas
where numerous infected spots occur, and the Brown Rot
or Rhizopus Rot fungus then attacks the flesh of the fruit.
The spots are invariably more numerous on the stem end
of the fruit. This is the result of where the spores land

108

1998 New Jersey Commercial Tree Fruit Production Guide