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is during periods of wet weather when soil moisture is
high.
 Ridomil can be applied in a band application using
an herbicide sprayer. In this case, the material should then
be irrigated with one-half to one-inch water to move it
into the root zone. Or alternatively, the fungicide can be
applied as a soil drench by mixing 16 oz Ridomil 2E in
100 gallons water and applying 2 quarts of the suspension
to a 4 ft by 4ft area around the tree. For larger trees,
increase the volume and area proportionately to cover the
entire root zone.
Ridomil Gold EC is a newer, more highly active
version of Ridomil. Only one-quarter as much product
needs to be used, compared to the 2E formulation, for
equivalent control.
Ronilan DF (vinclozolin)is a very effective fungicide
for controlling brown rot of stone fruit. It can be used
during both the blossom blight and fruit rot phases. This
fungicide is also effective in managing shot hole.
However, it is ineffective against scab and powdery
mildew.
Rovral 50WP (iprodione)is registered for control of
brown rot blossom blight and fruit rot of stone fruit. It is
also registered for control of rhizopus rot, but does not
have any activity against scab and powdery mildew. In
1996, the postharvest application of Rovral was removed
from the label. However, any older material with a label
indicating this use can still be applied for postharvest
disease control.
Rubigan 1EC (fenarimol)is highly effective against
scab, powdery mildew, and rust on pome fruit. It will
provide up to 96 hours of post-infection control against
scab. However, since it has a residual activity of only 3
days, it must be combined with a protectant-type
fungicide if spray intervals are longer than 7 days.
Sulfuris available as dry wettable powders and as
liquid lime sulfur. The lime sulfur form is best used for
dormant applications, as it can be injurous to both foliage
and fruit. The wettable sulfurs are much less injurous, but
can still cause some leaf burning and fruit russeting on
apple if used during hot weather (above 85F).
Newer sulfur formulations, such as microfine
Microthiol Special or That Big 8 flowable are much less
prone to injury. The labeled rate range for these materials
on stone and pome fruit is 8-16 lbs of actual sulfur per
acre. Typically, application at 10-12 lbs actual sulfur per
acre provides a good compromise between getting
adequate disease control and minimizing injury.
As a fungicide, sulfur is quite effective against
powdery mildews on pome and stone fruit.It also has
good efficacy against scab on peaches and nectarines.
However, it has little activity for control of cedar apple
rust, peach rusty spot, the fruit rots, and summer diseases.
Do not use sulfur within seven days after an oil
application.
Sulfur is not recommended for control of apple scab,
as it is only moderately effective. Many other superior
fungicides are available for this use. Similarly, on stone
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fruit, sulfur should not be used for brown rot control
during the critical bloom or preharvest period, particularly
if the weather is favorable for disease development.
However, sulfur can be used during the cover sprays when
fruit are less susceptible to brown rot infection.
Syllit 65W (dodine)is available for use on both
pome and stone fruit. On apple and pear, this fungicide
gives excellent control of scab, but does not control
powdery mildew, rust, rots, or most summer diseases.
Dodine can be used for post-infection scab control, but
must be applied at the highest rate and within 36 hours
from the start of the infection period.
Although a fungicide, Syllit is also registered for
control of peach bacterial spot. It should only be used for
this purpose when disease pressure is light to moderate.
On cherry, Syllit is excellent against leaf spot.
against brown rot and peach scab. On apple, it is effective
for controlling rust. This fungicide is not recommended
when conditions are extremely favorable for disease.
Thiram is also used as a deer repellent.
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Topsin-M 70W (thiophanate-methyl)is registered
for control of brown rot, peach scab, powdery mildew,
black knot, and cherry leaf spot on a variety of stone fruit
crops. On apple, Topsin-M is effective for scab, powdery
mildew, black rot, sooty blotch, and fly speck control.
Thiophanate-methyl is part of the same family of
fungicides as benomyl. Consequently, as with Benlate,
extended use of Topsin-M without other non-related
fungicides can result in the development of resistant plant-
pathogenic fungi. Furthermore, since these two fungicides
are related, fungi that become resistant to one of these
compounds are also cross-resistant to the other
compound.
Ziram 76DF (ziram)is a zinc salt derivative of
dithiocarbamic acid, the precursor to a wide variety of
organic sulfur fungicides, such as the EBDC's. On apple,
it can be applied from pre-bloom through cover sprays for
use in controlling scab, both cedar-apple and quince rusts,
sooty blotch, fly speck, bitter rot, and necrotic leaf blotch.
On pear, it also has activity against Fabraea leaf spot. On
both of these pome fruits, Ziram can be used as a mixing
partner along with a benzimidazole or sterol-inhibiting
fungicide.
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