Winter 2021 - 33

MATING DISRUPTION
Left, aerosol canisters that release puffs of pheromone
hang in trees and are replaced every season. Photo:
Suterra. Navel orangeworm damage, below, results in
significant economic losses every year. Photo: Jhalendra
Rijal, University of California
The layered approach
When mating disruption should enter the IPM scene for
a particular orchard should be decided by the grower and
the grower's pest control advisor (PCA). Where it's needed
most depends on the individual orchard, situation, pressure,
landscape and surrounding factors. And, due to aflatoxin
contamination, navel orangeworm damage must remain low.
Since IPM is a case-by-case, operation-by-operation
decision, growers can assess how much damage is eliminated
after adding mating disruption, then - after a few seasons of
successful use - can consider the possibility of reducing the
number of pesticide sprays.
How it works
Mating disruption research dates back to the 1970s, and
pheromonal communication has become less of a mystery.
Researchers are able to identify and isolate specific insect
pheromones and then replicate them, creating a synthetic
female pheromone that can be released in orchards to
confuse male insects looking to mate.
Frequency in an orchard varies among the options.
Canisters hang at about one per acre, Meso emitters at about
20 per acre and flowables can be sprayed multiple times,
depending on pest pressure and labeling instructions. Costs
vary, but generally range from $100-120/acre, and some
mating disruption companies offer both do-it-yourself and
full service options, such as custom orchard mapping for
placement, additional moisture monitoring, disease models,
and old dispenser recycling, with and without additional
charge. Each of these methods use the same pheromone and
similar amounts of pheromone over the season.
Currently, mating disruption falls in line after thorough
orchard sanitation and, at minimum, a pesticide spray at
hull split, making mating disruption more effective at further
reducing populations. A common mistake among growers,
Rijal said, is depending on pesticides to do all the work,
thus being lax about - or skipping - sanitation altogether,
thinking that the sprays have protected the mummies as well.
For a pest as determined as navel orangeworm, even a small
unprotected window in the season is enough to cause damage,
and leaving mummy nuts to remain on the tree is among the
worst scenarios for mating disruption to be effective.
Becoming more proactive
Depending on the situation, there have been reports of
growers being able to skip pesticide sprays because of lower
levels of pest pressure. As regulations and consumer and
market demands change, there could be more of a move away
from pesticides and a move up for mating disruption, bringing
it in as the second IPM step after sanitation, and changing
current cultural practices.
NATIONALNUTGROWER.COM 33
http://www.NATIONALNUTGROWER.COM
Winter 2021

Table of Contents for the Digital Edition of Winter 2021
