New herbicide labels for Michigan vegetable crops in 2024

Some new herbicides with known modes of action have been labeled for field use, and companies continue to add uses to older product labels.

In the past 20 years, there have been few new herbicides introduced and no new modes of action (MOA) have been brought to the market. Some new herbicides with known MOA have been labeled for field use, and companies continue to add uses to older product labels. There have been a few new uses labeled for vegetable crops, mostly through the work of IR-4. Several of the uses described here have been added to the 2024 edition of Michigan State University Extension Bulletin E0433, Weed Control Guide for Vegetable Crops. 

A new herbicide, Optogen (bicyclopyrone), has been labeled for several vegetable crops. Optogen is an HPPD inhibitor (Group 27) similar to Callisto (mesotrione) in chemistry and activity. Bicyclopyrone has been marketed previously as part of Acuron, a premix with s-metolachlor (Dual Magnum) and mesotrione (Callisto) for use in corn, including sweet corn. It has preemergence and postemergence activity against several broadleaf weeds and grasses. The label has an 18-month follow crop restriction for most non-labeled crops, so growers should have a plan for use that includes crops the next year if they choose to use Optogen.

Optogen has activity against many common weeds. However, in some situations it does not provide sufficient overall weed control if used alone. The label lists many difficult weeds as controlled or partially controlled. In general, it is most effective on very small weeds (up to 1 inch). Most larger weeds are not controlled by Optogen alone. Therefore, it should always be used in a tank-mix with other herbicides.

Labeled crops include broccoli, garlic, horseradish, onion, green onion, rosemary, strawberry, sweet potatoes and watermelon. The uses for all crops include postemergence and/or shielded applications. In some crops (garlic, onion, green onion, horseradish, sweet potato, watermelon) it can be applied preplant or preemergence also. Most labeled crops may be injured if plants are sprayed over the top with Optogen. Growers who plan to use Optogen should read and study the label carefully to avoid misuse and potential crop injury. 

Rely 280 (glufosinate) has been labeled for use on several vegetable crops, including cucumber, melons, pepper, summer squash, tomato and watermelon. Rely has postemergence activity against most broadleaves and grasses. It must be applied as a directed or shielded spray to row middles. In many situations, Rely may replace Gramoxone (paraquat) as a postemergence directed spray. It will kill most vegetable crops if there is direct plant contact. The Rely supplemental label is not listed on CDMS. Growers should ask chemical suppliers for a copy of the label.

The indemnified 24c label for Reflex (fomesafen) has been renewed for another five years. Cucumber and dry bulb onions have been added to the label. In cucumbers, Reflex may be applied preemergence after seeding to improve control of several broadleaf weeds, including common purslane and pigweeds. The Reflex label includes a restriction on repeated use; it may only be applied once in two years to any field. This is the case for all Reflex applications in Michigan. Rotational restrictions can also be long for some crops. Growers who plan to use Reflex should have their follow-crop plans in place before application.

In dry bulb onions, Reflex may be used in one application postemergence. It is similar chemically to GoalTender (oxyfluorfen) and may be used as another postemergence application to control broadleaves. It cannot be used two years in a row on the same soil. 

The Reflex indemnified label is available on Syngenta’s website. Each farm must create an account on the website, log in and download the label. Applicators must have a copy of the label in hand when using Reflex. Other crops on the indemnified label are pea, pepper, pumpkin and squash. Growers must accept all potential crop injury liability for use of Reflex on these crops.