Farming economics are getting tougher for some growers, and cutbacks will be made.
In short, yes, herbicides can be a part of that, but there are a few factors to help determine where and how much. Not the least of which is the age of the trees and a grower’s tolerance for weeds.
Stay the course on young trees
Young plants in general are much more sensitive to competition, and young trees have fewer available weed control tools. Excess weed competition with young trees can slow their growth, and the effects of that slow early growth can linger for years. Fewer strong roots means stunted trees, which means a long game of catch-up.
So there’s a real risk when cutting back on weed control in the first 3-5 years of tree growth. But weed competition poses a far smaller risk once the trees are well established.
Skip the final ingredient
Most importantly, getting the best effects possible out of a spray program almost goes without saying. This especially means getting the timings right: timing with appropriate weed size for postemergence herbicides, and timing relative to rainfall for preemergence herbicide incorporation.
Many weed control programs include several, sometimes three to four, components in a tank mix. In tougher economic conditions, growers can take a look there, particularly at those third or fourth components that may only be helping to tackle that last percentage of weed control.
Growers can ask themselves, “If I’m adding that last tank mix component to bump my weed control from 95% to 98%, can I live with taking that last one out?” said Brad Hanson, weed scientist with the University of California Cooperative Extension.
From a winter pre-emergent perspective, the foundation product is often doing most of the work. In some cases, the additional herbicides in the mix may be needed to broaden the weed control spectrum, but, in others, they may only be helping to get those last few weeds or to make up for poor timing.
“Be really thoughtful about why you’re choosing each herbicide in the mix, and whether the value they bring is worth the cost,” said Hanson.
Shrink the spray strip
The reduction of tank mix partners can be followed with a reduction in the size of the spray strip. For example, blocking a nozzle or two on the inside of the spray boom can reduce a 12-foot strip to 8 feet, saving one-quarter to one-third of the treated acre.
Narrowing the spray strip as much as possible while still covering the middles with a single mow pass can result in substantial savings. Likewise, weed management intensity can be reduced by letting the weeds get a little bigger than normal, but then mowed before the weeds mature to seed.
“If you can time mowing before the weeds are done flowering, they’ll have fewer mature seeds, and that means there’s less seed to produce weeds next year, two years, or five years down the road,” Hanson said. “If you can time a mowing or spray operation to reduce operational costs this year, but also still reduce the long-term impact of having a weedier orchard, that’s one way to do it.”
Make sure water can reach
A higher tolerance for orchard weeds means a possibly indirect issue of inhibited water flow, including interfering with micro-sprinklers and other irrigation, which can have an effect on tree health.
Cutting back on herbicides isn’t a trade for potentially costly new issues. Water and fertilizer still need to get to all the places they need to go, so control weeds well enough that irrigation uniformity remains reasonable even with slightly relaxed weed control tolerances in the orchard, Hanson noted.
“In tough economic times, it’s about reducing weed management intensity, both input costs and timing,” he said. “No matter what we do for weed control, we want to have a good plan and implement it well.”
Photo: Brad Hanson, University of California
Other Articles
The Element – Aigen’s autonomous robot powered by renewable energy
Potato sensor upgrade sends data from deep inside the storage pile
