By Jeff Pacheco, technical sales agronomist, DuPont Crop Protection

Q: Can you provide recommendations for season-long weed control?

The last few years have made seasonal weather patterns less predictable on the West Coast. But one thing you can count on when fall or winter rains arrive is that weeds will quickly follow.

Avoid the challenges of controlling late-winter and early-spring weed flushes in your orchard by taking a more proactive approach to weed control starting this fall. Stopping weeds before they emerge is key to staying ahead of weeds throughout the year.

I recommend these strategies for effective season-long weed control in orchards.

1. Start clean after harvest.

Removing leaves, trash, large weeds or large weed carcasses from under trees is a good post-harvest practice for many reasons. For one, it lets you spot late-germinating weeds while they’re still small. A fall burndown application with a postemergence herbicide might be a necessary late summer or early fall cleanup step.

Two weeds that often germinate again in the fall, marestail and fleabane, are becoming more challenging to control because of increased resistance development to contact herbicides such as glyphosate and paraquat. DuPont™ Matrix® SG herbicide is a good alternative for control of these two tough broadleaf weeds and can be tank mixed with a variety of other herbicide modes of action to achieve customized weed control, with resistance management. Matrix^® SG can be applied as a single broadcast application in fall or early winter, or as sequential applications in fall and spring, depending on weed pressures and moisture patterns.

2. Get ahead of winter weed growth cycle.

Most orchards are plagued by a healthy crop of young weeds when fall or winter moisture is plentiful and soils begin to warm in the spring. A preemergence, residual herbicide applied in late fall, prior to a rain event, can provide effective control through the winter and early spring months. Following that with a sequential herbicide treatment in the spring, usually in mid to late March, will allow growers to get consistent and extended weed control while taking advantage of California’s typical rainfall patterns.

In field studies, sequential applications in the fall and spring that included Matrix^® SG as the foundational residual herbicide achieved excellent preemergence weed control in those seasons, and extended residual control into late spring and summer. Applying Matrix^® SG in a sequential treatment program – one 50 percent or less banded treatment in the fall and a second 50 percent or less banded treatment in the spring – will reduce the need to use multiple applications of burndown herbicides during the busy late spring and summer months.

3. Aim for broad spectrum control.

Choosing a foundational herbicide that controls a wide range of broadleaf and grass weeds will save you time and money. Matrix^® SG controls 10 tough grass species and 37 common broadleaf weeds, including fleabane and marestail.

A sequential program also allows for tailoring a tank mix to control the orchard’s most important weed problems in the late fall, winter, spring and early summer months. Using Matrix^® SG is a tank mix with DNA herbicides, such as Prowl and Surflan, or Alion have provided the most effective and extended summer grass control when applied in the spring.

4. Maintain flexibility.

A herbicide that offers both preemergence and early postemergence control of difficult weeds can also provide application flexibility. Matrix^® SG provides several key benefits:

A well-planned preemergence weed control program is more effective and provides a good return on a grower’s investment. By achieving more consistent control, it helps avoid the cost and hassle of follow-up or rescue treatments and working around unpredictable weather conditions during the fall and winter season. It’s the best way to stay ahead of weeds and improve orchard productivity.

_{For more information on how Matrix® SG can help you prepare for next year, please visit} matrix.dupont.com_.

_{Always read and follow all label directions and precautions for use. DuPont™ Matrix® is not registered in all states. Contact your DuPont representative for details and availability in your state. Unless indicated, trademarks with ®, ™ or sm are trademarks of DuPont or affiliates.  © 2017 DuPont.}

_{Alion® (Bayer); Prowl® (BASF Corporation); Surflan® (United Phosphorus Limited).}