New Weed Control Options for Leeks

 

 

Leeks are in the onion family and are increasingly important crop in Monterey County. In 2017, there were 475 acres produced worth $8.6 million. They are mostly established by transplanting and days to maturity is generally 120+ days, but varies widely depending on the time of year and market demand. Given the long crop cycle and the lack of a dense crop canopy, leeks are susceptible to successive waves of weed emergence. Growers complain that leeks “blow up” weed populations by allowing a significant number of weeds to mature and set seeds.

 

The preemergent herbicides DCPA and pendimethalin are registered for use and provide good weed control. However, post emergent herbicides such as bromoxynil and oxyfluorfen which provide excellent control of escaped weeds in onion production are not registered on leeks. In Canada prometryn is registered for use on leeks. In 2016, we began studying this material for use on leeks to bringing it into the US market. This project is now supported by the IR4 program and they are evaluating crop safety and developing a tolerance to eventually bring it to market.

 

 

Prometryn is particularly useful because it controls emerged weeds and has preemergent activity as well, which fills a need for this long-season crop. Table 1 shows weed counts and phytotoxicity ratings for a trial established on August 25, 2017. On the September 20 evaluation date, there was slight phytotoxicity in the prometryn treatments on the leeks, but no difference between the two application timings. Phytotoxicity consisted of a bending down of older leaves (Photo 3). The plants appeared to have recovered for the most part from this issue by the October 10 and November 9 evaluation dates, but bent leaves could still be observed to a small degree. Bromoxynil caused burning on the tips of the leaves that was evident on all evaluation dates. All rates and timings of prometryn eliminated weeds in the plots (Photos 1 & 2). There was no statistical difference in yield, but there is a trend that higher rates of prometryn had lower tonnage than the untreated control.

 

The potential for prometryn as a preemergent herbicide for use on leeks is quite exciting. It has the potential to provide a level of weed control in this crop that we have not seen. We are exploring its use on other allium crops as well and recently observed good safety on onions in one trial when it was applied at the 5th true leaf stage.

 

 

 

 

Video: Winter Canola Trial in Mississippi | Can It Work for Double Cropping? | Pioneer Agronomy

Can winter canola open new opportunities for growers in the Mid-South? In this agronomy update from Noxubee County, Mississippi, Pioneer agronomist Gus Eifling shares an early look at a first-year winter canola trial and what farmers are learning from the field.

Planted in late October on 30-inch rows, the crop is now entering the bloom stage and progressing quickly. In this video, we walk through current field conditions, fertility management, and how timing could make this crop a valuable option for double-cropping soybeans or cotton.

If harvest timing lines up with early May, growers may be able to transition directly into another crop during ideal planting windows. Ongoing field trials will help determine whether canola could become a viable rotational option for the region.

Watch for:

How winter canola is performing in its first season in this Mississippi field

Why growers chose 30-inch rows for this trial

What the crop looks like as it moves from bolting into bloom

Fertility strategy, including nitrogen and sulfur applications

How canola harvest timing could enable double-cropping with soybeans or cotton

Upcoming trials comparing soybeans after canola vs. traditional planting

As more growers look for ways to maximize acres and diversify rotations, experiments like this help determine what new crops might fit into existing systems.