glyphosate (numerous product names)
Rate Read label carefully for crops listed and geographic location.
Time Apply 6 to 8 oz/A to suppress (chemically mow) perennial grass covers between tree rows in orchards.
Remarks Use the 8 oz/A rate to treat tall (coarse) fescue, fine fescue, orchardgrass, or quackgrass covers. For best suppression of these species, add ammonium sulfate at 1.7 lb/10 gal of spray solution. Use the 6 oz/A rate, without ammonium sulfate, when treating Kentucky bluegrass covers. Apply treatments in 20 gal/A spray volumes to actively growing grass covers. For best spray distribution and coverage, use flat fan nozzles. Additional nonionic surfactant may be added at 0.5% concentration when using surfactants with at least 50% ai, or a 1% surfactant concentration for those with less than 50% ai. For best results, mow grass in spring for uniformity, then apply appropriate rate 3 or 4 days after mowing. Low rates will not adequately suppress broadleaf weeds such as dandelion or plantain. If broadleaf weeds infest more than 10% of ground cover, tank mix 2,4-D labeled for orchard use.
Caution Chemical mowing is not recommended if orchard weed management is primarily reliant on glyphosate. Low rates of glyphosate applied multiple times per year may significantly increase the chance of selecting glyphosate resistant populations. Do not treat grass covers under poor conditions such as drought stress (drip irrigation), disease, or insect damage; suppression may be poor.
Site of action Group 9: inhibits EPSP synthase
Chemical family None generally accepted
sethoxydim (Poast)
Rate 0.09 lb ai/A (0.5 pint/A Poast)
Time Apply to grasses in orchard floor middles one time only, to suppress growth.
Site of action Group 1: acetyl CoA carboxylase (ACCase) inhibitor
Chemical family Cyclohexanedione