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rapidly. Do not treat weeds that are dormant or under
stress from drought, extreme heat, cold, or other adverse
growing conditions.  The optimum stage of growth
depends on the herbicide used and the weed species.
Most herbicides that enter the plant through the leaves
need a minimum rain-free period of at least 8 hours after
application for maximum effectiveness. Postemergence
herbicides may be selective or nonselective and work only
where they contact the plant or translocate throughout the
plant.
Selectivepostemergence herbicides kill only certain
weeds. Plants that are not susceptible will not be harmed.
Dalapon 85/Dowpon M and 2,4-D are examples of
selective postemergence herbicides. Dalapon 85/Dowpon
M kills grasses. 2,4-D affects only broadleaf plants
(including fruit trees).
Nonselectivepostemergence herbicides kill or injure
any treated plant. They may be contactor translocated.
Contactherbicides work only where they are placed.
Thorough spray coverage is essential for good results.
Roots of established perennial weeds may survive.
Translocatedherbicides move in the weed after
treatment. Application at the proper growth stage will
often result in good control of the roots as well as tops of
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established and perennial weeds. Translocated herbicides
work slowly to provide time for movement throughout
the plant. Results may not be evident for several weeks.
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Improperly applied herbicides or herbicides applied
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above recommended rates may cause crop damage.
Residual herbicide rates must be matched with soil
type and percentage of organic matter to obtain good weed
control and crop safety (see Table 19). Adjust by
changing tractor speed and maintaining pressure when
spraying an orchard with soil that requires different
herbicide rates. Determine type and percentage of organic
matter for each soil on the farm with a separate soil test for
each soil.
Herbicide applicationshould be accomplished with
a "conventional" fixed-boom sprayer calibrated to
accurately deliver 40 to 60 gallons of water per acre using
flat fan nozzles and 30 to 40 psi, unless otherwise stated.
Herbicide rate recommendations are made on a
broadcast basis(amount of herbicide applied per sprayed
acre).
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Postemergence(selective)
2,4-D1FGFGFG--------
Fusilade DXG--GGG--GGGG
Kerb--G--G--G--G--G
PoastGGG--GGG--G--
Postemergence(nonselective)
Gramoxone Extra1GGGGGGGGGG
RoundupUltra1GGG2G2GGG2G2GG
G = GoodL = Labeled (data insufficient or not recommended)
F = Fair (use with care)-- = NOT LABELED (DO NOT USE)
P = Poor (not recommended)
1Do NOT allow spray to contact young green bark.
2Do NOT allow spray to contact any part of tree, including mature bark (labeled for use only in New Jersey and certain other states).
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