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 Benlate-resistant strains of the apple scab and brown
rot fungi have been found in New Jersey where this
material, or the related Topsin-M fungicide, have been
used frequently. Consequently, Benlate should only be
used in combination with protectant fungicides. Benlate is
damaging to predator mites.
Blue Shield DF (cupric hydroxide)- see copper
(fixed)
Bordeaux Mixture (copper sulfate + calcium
hydroxide), which was discovered in 1882 in a grape
vineyard in Bordeaux, France, controls many fungus and
bacterial leaf spots, blights, downy mildews, and cankers.
However, it is also phytotoxic to plants and often has
compatibility problems with other materials. For these
reasons, Bordeaux has largely been replaced by fixed or
insoluble copper fungicides (see Copper, fixed).
Although Bordeaux displays foliar phytotoxicity, it
can still be useful as a dormant spray for control of peach
leaf curl and fire blight on apple and pear. For leaf curl, a
common formula is 4-6-100, while for blight, a good
mix is 8-8-100. In both cases, the first number is pounds
of copper sulfate, the second number is pounds of hydrated
spray lime, and the third is gallons water.
Botran 75WP (dicloran)is extremely effective
against Rhizopus rot on stone fruit. It will also control
brown rot, but higher rates are necessary. It is registered
for applications during the blossom blight and preharvest
fruit rot periods on peach, nectarine, plum, prune, and
sweet cherry. For postharvest use of dicloran, see Allisan.
Bravo Weather Stik, Bravo 720 (chlorothalonil)
will provide good control of brown rot blossom blight
and scab on stone fruit. Blossom blight applications
should be made from popcorn through petal fall. In New
Jersey, Bravo is now registered for one additional
application at 10-14 days after the shuck-split spray. This
should allow extended protection for peach scab control.
Bravo is also effective against leaf curl, coryneum blight,
and cherry leaf spot.
Captan 50WP, 80WP (captan) is an excellent
protective fungicide for control of scab, frog-eye leaf spot,
black rot, white rot, Brook's spot, bitter rot, sooty blotch,
fly speck, and calyx-end rot on pome fruit. Captan can be
used for post-infection control of apple scab, but must be
applied within 18 hours from the beginning of an infection
period. This fungicide will not control cedar-apple rust
and powdery mildew.
On stone fruit, captan provides very good control of
brown rot and scab. It is ineffective for powdery mildew
and peach rusty spot. Mite problems in Captan-treated
blocks are generally more severe than where other
fungicides are used. Captan is not compatible with oil or
lime.
Champ Formula 2 (copper hydroxide)-see copper
(fixed)
Copper (fixed)is a form of copper compound in
which the copper ion is fixed securely to the molecule.
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The resultant chemical is only slightly water soluble,
which makes it less phytotoxic than Bordeaux, but also
less effective as a fungicide/bactericide. Nevertheless, fixed
copper materials such as Kocide, Tennecop, Champ, and
Blue Shield are still useful for bacterial leaf spot, bacterial
canker, peach leaf curl, and fire blight.
Athough safer than Bordeaux, fixed copper materials
should be applied with added spray lime to further reduce
the risk of plant injury. Add 2 lbs of lime to each pound
of fixed copper. An exception to this rule is Tenncop 5E,
which provides good control of bacterial leaf spot with
much less phytotoxicity than any other formulation
tested.
Repeated use of coppers for bacterial leaf spot and
bacterial canker control can result in the development of
copper-tolerant strains of the bacterium.
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Elite 45DF (tebuconazole)is a new sterol inhibitor
fungicide registered for control of brown rot blossom and
fruit rot on peach, nectarine, and cherry. It is also effective
for use on leaf spot and powdery mildew of cherry. As
with other sterol inhibitors, the potential for resistance
development exists. Thus, Elite should be applied as a
mix or in alternation with protectant fungicides.
Ferbam 76WDG(carbamate) is a protectant-type
fungicide with good efficacy against cedar-apple rust and
as a fall or spring dormant spray for peach leaf curl. It is
also effective for black knot on cherries and plums and for
leaf and fruit spot on pears. Ferbam will russet sensitive
apple varieties such as Golden Delicious, but is safe on
Red Delicious and Rome Beauty. This fungicide has only
moderate activity for control of apple scab, sooty blotch,
cherry leaf spot, and brown rot of stone fruit.
Funginex 1.6EC (triforine)is a locally systemic
fungicide effective for peach and nectarine brown rot
control during both the bloom period the preharvest
period. It can also be used for blossom blight on apricots,
cherries, plums, and prunes, but should not be applied on
these crops after petal fall or fruit russeting may develop.
Funginex is also effective against peach powdery mildew
and rusty spot, but is quite weak against peach scab.
Funginex is also registered for use on apples for
control of scab, powdery mildew, and rust. Applications
are limited to the period from half-inch green tip to petal
fall. This material is highly effective for post-infection
scab control when applied at full rate within 72 hours of
the start of wet period suitable for scab infection.
Funginex has a very short residual activity of only three
days, and therefore should be mixed with an unrelated
fungicide, such as Captan or Benlate. This approach is
also important for reducing the risk of developing resistant
pathogens.
Indar 75WSP (fenbuconazole)is a highly effective
fungicide for control of brown rot blossom blight and fruit
rot on peach, nectarine, cherry, and apricot. It also
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