It’s the second week of April and if you grow either pumpkin or squash, the notion of weed control has undoubtedly been on your mind. On May 29 2020, Reflex herbicide (fomesafen, Syngenta) was given a 24(c) label (local needs exemption) in Ohio for use on cucurbits.
What does Reflex bring to the weed control game to complement other currently labeled herbicides? Reflex is a pre-emergent herbicide which should be applied after seeding but before crop emergence. The primary fit would be against small seeded broadleaves such as lambsquarters, purslane, common ragweed, nightshade and pigweeds (see full efficacy chart here https://mwveguide.org/uploads/pdfs/2021-herbicide-efficacy-table.pdf).
As always, choose fields with low weed pressure if possible and start with a relatively clean field either through stale seed bed or use of burn down herbicides (glyphosate, paraquat). Use pre-emergent herbicides followed by post emergent herbicides if necessary to get weed control further into the season, then mop up with spot sprays as needed. The full list of herbicide options can be found in the 2021 Midwest Vegetable Production Guide pg. 102 (https://mwveguide.org/uploads/pdfs/2021-cucurbit-crops.pdf).
In July 2020, members of the department of Hort and Crop Science and IPM Program put out a small late summer herbicide weed screen trial at the Western Ag Research Station which was reported extensively in the 2020 virtual field day video segment starting at the 10:01 mark (https://u.osu.edu/jasinski.4/pumpkins/). In this 16 minute video, Reflex alone plus combinations of Reflex with Dual II Magnum, Sandea and Strategy are shown and discussed.
There is a Vegblog post on June 16, 2020 with additional comments about this herbicide concerning direct seeded and transplanted pumpkin and squash (https://u.osu.edu/vegnetnews/2020/06/16/whats-new-with-herbicides/).
Be sure to read the entire Reflex 24(c) label and understand the warnings about its use:
– Needs 0.5-1” rain or irrigation to be activated
– Sensitivity is possible on both pumpkin and squash hybrids – test on small area first
– Butternut is very sensitive to Reflex – test on small area first but expect thinning or yield reduction
– Cold and wet soils during germination and seedling growth may result in delayed maturity and / or yield.
– Heavy rain shortly after transplanting may also result in delayed maturity and / or yield.
– Reflex herbicide rates below 1 pt/A are not intended to be used as a stand-alone weed control program and should be used with other herbicides and/or other methods of weed control that support weed resistance management.
– Carryover injury possible and beware of rotation restrictions
The research and demonstration behind these new uses was paid for in part by the IR-4 Program, the Ohio Vegetable and Small Fruit Research and Development Program (OVSFRDP), and the IPM Program, and could not be conducted without the OARDC research stations and support from the chemical companies.
What plans are in store for 2021? We have another herbicide screening trial that will be rated for percent control of weeds and a hybrid sensitivity trial where we will look at potential seedling emergence and injury on pumpkin, squash and butternut as described by the label warning.