Growing multiple crops a year in the same ground has its own set of challenges apart from the goal of producing a high-quality, high-yielding crop with all the desired market characteristics. Take, for example, broccoli, grown in the desert valleys around Yuma and Coachella, and the California coastal valleys, where 2 to 3 crops a year is the goal.
Growers are looking for large heads of good color, a nice rounded head, no interior hollowing or pitting, and an overall deep, uniform color. Broccoli heads with these characteristics meet the standards for the premium, or export grade, and demand the highest price.
Any tool that would help cut harvest costs and shorten the harvest period would also allow growers to produce broccoli of this quality more economically, and allow growers to get back into the field for the next crop sooner.
“Harvest costs, including cutting, boxing and cooling, are half the total expense of growing broccoli,” says Steve West, contract researcher who operates in Yuma, Ariz., and the Coachella Valley in Southern California. “We often make four passes in a field during harvest; anything we can do to lessen this, such as making fewer passes, helps to cut costs. If we could cut more broccoli at once, this would cut our costs. Ideally, we would get 800-1,000 boxes in one harvest and call it quits. Then we could turn the field over and get it ready for the next crop sooner.”
West, who evaluates new technology for Desert Mist, a grower for Ocean Mist, has been conducting trials for several years with a product called AuxiGro that has increased the percent of total yield in earlier harvests. In one year, for example, the use of the product put 86 percent of the total yield in the first two harvests, compared to 72.6 percent for the controls. AuxiGro has recently been approved by the California Department of Pesticide Regulation for use on broccoli.
“With AuxiGro, I don't believe we get an earlier crop,” West says, “but a more uniform and higher-yielding crop. We would like to consistently get harvest passes down to one to three rather than four to six, which is average.”
In current trials, West is trying to “fine tune” the use of AuxiGro, he says. “This is like Gibb on grapes or Pix on cotton” where growers will discover the optimum use of AuxiGro for their growing conditions and production practices.
Uniformity of harvest measured by number of heads of a similar size in each harvest with the use of AuxiGro was demonstrated in a Watsonville trial where the grower's standard plots yielded 23 boxes of size 18s, 68 boxes of 14s, and 114 boxes of 12s. By contrast, the AuxiGro plots yielded no 18s, 52.6 boxes of 14s and 184 boxes of 12s. In independent trials, average yield increase over untreated broccoli in Texas, Santa Maria, Tulare, San Joaquin, and Riverside was 30 percent, increasing crop value by more than $1,300, according to company-supplied data.
Quality factors that have been demonstrated in trials include less hollow core and more heads per plant.
Applied as a broadcast spray at specific stages of crop development, AuxiGro works by triggering the plant's stress-response mechanism, which, in turn, enhances nutrient uptake, movement and utilization. According to Elaine Hale, contract researcher in Santa Maria, AuxiGro-treated plants “are strong enough to resist physiological and pathological effects. We have observed the benefits of early application for resisting damping off because AuxiGro boosts the immune system of the plant,” she reports. Damping off is a problem in broccoli transplants, she says. “In this area, most broccoli is transplanted, and we need a tool to help prevent damping off.”
A transplant is weaker than direct-seed plants, points out John Teixeira, who is in charge of greenhouse operations for Teixeira Farms, Santa Maria, Calif., and a cooperator in AuxiGro trials. “Direct-seeded plants are more able to fight off diseases, but we have to weigh the longer time in the field of direct-seeded plants versus tying up the ground. Our goal is to use the ground as many times as possible, and with our own nursery, we can economically grow our own transplants and turn the ground over more quickly,” he explains.
“Growers should put AuxiGro in the tank with fungicides and insecticides as an ongoing program,” Hale suggests. “Because AuxiGro is a tool that can help protect plants against extreme conditions, it could be used if you have a sandy field that's 30 days to market, and irrigation is not immediate. Also, it can get very cold here in June,” she says. “You may have cold, overcast weather when it is supposed to be hot, and vice versa. The plant says, ‘this is not my weather.’ Maybe we can manipulate that by protecting plants with AuxiGro. This is something we should investigate.”
In a 2003 AuxiGro trial at Teixeira Farms, Hale recorded a 21 percent increase in broccoli yield (by weight) with three applications of AuxiGro at four ounces per acre. The company recommends four 4-ounce applications at 14-day intervals beginning at 7-10 days post transplant (or 4-6 — leaf stage). Water and nutrition management must be watched in AuxiGro treated fields, according to the manufacturer, Emerald BioAgriculture. Because the crop is producing a higher yield, you must adjust nutritional and irrigation programs to maintain crop health.
In addition, AuxiGro should be applied with a calcium-based foliar product along with a silicone surfactant. It is important to adjust the final spray solution to pH 6.0-7.0.