2,4-D (Saber, Orchard Master, Unison, Weed Rhap A-4D, Embed Extra)
Rate 0.7 to 0.95 lb ae/A (1.5 to 2 pints/A Saber; 3 to 4.5 pints/A Unison; check labels for specifics)
Time Apply in 100 gal/A water; add nonionic spreader-sticker. Apply to suckers 6 to 9 inches long, but better results are observed when treating suckers less than 3 inches. Limited to four applications per season with at least 30 days between applications.
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. 2,4-D drift delays nut abscission. Use of drift reduction nozzles and low volatility formulations is advised. Refrain from treating field when air temperature is expected to exceed 85 F within a few days of application.
Caution Preharvest interval is 45 days. Grazing is prohibited. Poor sucker control is observed when application rate is lower than specified. Application in 100 gal/A are better suited for spot treatments. Better sucker control with broadcast applications observed when following recommendations listed under orchard floor section.
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
1-Naphthaleneacetic acid NAA (Tre-Hold Sprout Inhibitor A-112)
Nonbearing hazelnuts only
Rate 1 % ai v/v diluted in water (10 fl oz of Tre-Hold Sprout Inhibitor A112 per gallon of water)
Time Apply in 20 to 44 gallons per acre up to twice per season, when suckers are 3 inches or less. Add a nonionic surfactant and ammonium sulfate to spray solution
Remarks NAA is a plant growth regulator and prevents sucker growth for about 3 to 5 weeks. Foliar absorption is important, so apply to actively growing suckers. Direct spray toward green suckers at tree base. Spot treatment of sensor sprays are necessary to limit treatment costs. Tank-mixes with burndown herbicides like carfentrazone or saflufenacil provide better control.
Caution Avoid windy conditions and drift. On. Do not retreat in less than 30 days for best results.
Site of action Group 4: synthetic auxin
Chemical family Phenoxy acetic 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 Restricted use pesticide due to acute toxicity for retail sale to and use only by certified applicators - not to be used by uncertified persons working under the supervision of a certified applicator. 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
pyraflufen (Venue)
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
saflufenacil (Treevix 70% WDG)
Apple, pear, hazelnuts and walnuts only
Rate 0.044 lb ai/A (1oz/A)
Time Directed postemergence.
Remarks Controls annual broadleaf weeds and suppresses growth of some perennials. Does not control grasses. Adjuvants are needed to maximize burndown control. Up to 3 applications allowed each year (3 oz/A). Preharvest interval of 7 days on nuts. Trees must be established for 12 months. Protect bark of young (2-3 year old) trees. Consult label for accepted crop use.
Caution Contact with foliage will cause damage. Causes substantial but temporary eye damage; PPE includes protective eyeware.
Site of action Group 14: Protoporphyrinogen inhibitor
Chemical family Benzamide