How We Grow

2021 Nov/Dec How We Grow

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NOW Tools Create Year-round Management and Have Additional Benefits With the proven ability of navel orangeworm (NOW) populations to spike from year to year, more tools to monitor and employ control practices for the pest are proving viable for growers and create a year-round management approach. Recent research has also identified an additional benefit to the anchor of NOW integrated pest management, mummy removal, making the practice worth it even more. Learning from the past Some seasons are permanently engrained in the heads of growers and researchers because of unprecedented negative impacts to the crop. For almond growers, one of those cases is navel orangeworm damage in 2017. "2017 was a nightmare," said Mel Machado, member relations director for Blue Diamond Growers. "We had growers who had never been above 2 percent damage in their lives, who found themselves living between 8 and 12 percent damage." Machado has spoken at several industry events since 2017, including ABC's Navel Orangeworm Summit in 2019, presenting on the relationship between NOW damage levels and the possible financial impact. Assuming a 2,500 pound per acre crop of Nonpareils, at a market price of $2.50 per pound, 1 percent damage from NOW equates to a loss of more than $158 per acre. At 2 percent damage, growers could expect a loss of more than $436 per acre. 1 Machado notes that those potential losses exceed $1,000 per acre at as little as 5 percent damage. History is known to repeat itself NOW damage numbers have dropped since 2017, likely due to the awareness of financial impacts and the education around winter sanitation. But what factors led to the spike in NOW in 2017? Machado said a big factor is something familiar to present day. "Coming out of a drought. We had poor sanitation and the mummy load had built up in the fields," he said. "It was a year where we got some heat during hull split – much like this year. Hull split slows down because of the stress on the trees but the worm continues to progress, so we extended our susceptibility." Machado's explanation sounds a lot like the 2020-21 growing season. Water supply was stretched thin this year with poor snowpack accumulation. With lower prices during much of the season, growers likely cut input costs where they could. "Talking to growers this year, we know they are looking to cut costs where possible," said Michael Roots, field outreach and education specialist for ABC. Roots noted that several reports from the field about NOW were favorable but added we will see a slight increase in the final numbers just because of a favorable 2019-20 growing season. "Last season happened to be a really low-pressure year for navel orangeworm," he said. "It looks like damage is probably going to be up a little bit from last year due to a bit more pressure, but also with the current crop being smaller those percentages may come out a little higher." ABC's senior pest management specialist Drew Wolter agreed with the similarity between this season and the often-mentioned 2017 year. "Early flight activity this year is higher when compared to historical averages, mimicking 2017's numbers," Wolter said. "Egg laying was considerably earlier than prior seasons and trap counts remained higher than historical averages throughout the season and valley." PEST MANAGEMENT Mating Disruption Tools for Navel Orangeworm Monitoring Tools for Navel Orangeworm Watch now 1 "How Much Does NOW Damage Cost" Winter sanitation is essential for effective integrated pest management of navel orangeworm. 7

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