2,4-D (Saber or Orchard Master)
Rate 0.7 to 0.95 lb ae/A (1.5 to 2 pints/A Saber)
Time Apply in 100 gal/A water; add nonionic spreader-sticker. Apply to suckers 6 to 9 inches long.
Remarks Spray to runoff as needed, up to four times per year from April through August. Use large-orifice nozzles to reduce possible drift. Mimics natural plant hormones.
Caution Preharvest interval is 45 days. Grazing is prohibited.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic acid
carfentrazone-ethyl (Aim EC)
Rate 0.031 lb ai/A (2 fl oz/A Aim EC)
Time Direct spray to immature green suckers at base of tree.
Remarks Read label for additional options.
Caution Care must be taken not to allow spray mist to contact desirable fruit, foliage or green stem tissue. Do not apply more than 0.031 lb ai/A (2 fl oz/A Aim EC) per application. Do not apply more than 0.124 lb ai/A (7.9 fl oz/A) per season.
Site of action Group 14: inhibits protoporphyrinogen oxidase
Chemical family Triazinone
glufosinate ammonium (Rely 280)
Rate 1 lb ai/A (1.75 quarts/A Rely 280 and others)
Time Direct spray to cover all sucker foliage.
Remarks Split applications about 4 weeks apart to improve control. Avoid contact with immature or green bark. Do not use adjuvants. Spot spray application to green suckers are not allowed because tree injury may occur. Maximum use per season is 4.5 lb ai/A (246 fl oz of product).
Site of action Group 10: inhibits glutamine synthetase
Chemical family Phosphinic acid
paraquat (Gramoxone SL 2.0)
Rate 0.625 to 1 lb ai/A (2.5 to 4 pints/A Gramoxone SL 2.0)
Time Apply 3 to 4 times per season, when suckers are 6 to 9 inches long but before they become woody.
Remarks Add a nonionic surfactant or crop oil concentrate as label specifies, taking care to avoid anionic formulations that react in the tank to form insoluble precipitates. Direct spray toward green suckers at tree base. Acts on contact; absorbs energy produced by photosynthesis, forming peroxides that disrupt living cells.
Caution A restricted-use herbicide. Do not ingest or inhale spray mist. Wear protective face shields, respirators, and clothing. Do not allow spray to contact foliage or fruit. Avoid windy conditions and drift. Do not graze treated areas. Do not apply when nuts are on the ground. Maximum of 5 applications per year.
Site of action Group 22: photosystem I electron diversion
Chemical family Bipyridilium
Rate 0.004 to 0.0053 lb ai/A (3 to 4 fl oz product/A)
Remarks Requires thorough coverage for good sucker control. Effective if shoots are young and small. Adjuvants such as a COC, MSO or an OS (Organo-Silicone) are recommended.
Caution Do not apply more than twice in one season. Avoid contact with desirable foliage, green bark, or fruit.
Site of action Group 14: protoporphyrinogen oxidase inhibitor
Chemical family Phenylpyrazole