Improving the sustainability of avocado lace bug (Pseudocysta perceae) management through economic threshold analysis

Commodities

• Fruits: avocados

Practices

• Pest Management: economic threshold

Avocado lace bug (ALB), Pseudacysta perseae, is a
phloem-feeding insect pest of avocado trees and is invasive to
California, Florida, and Hawai’i. Feeding by ALB nymphs leads to
the accumulation of large areas of necrosis on avocado leaves and
eventual tree defoliation. ALB-induced leaf necrosis begins as
areas of chlorotic tissue that grow larger as nymphs eclose,
feed, and develop. Eventually, these necrotic areas become
sufficiently large that the leaves are dropped from the tree
prematurely. A sufficient number of early leaf drop events
between periods of flowering and fruit set in avocado trees has
been suggested to negatively affect avocado yield, likely through
decreased photosynthetic activity and reallocation of resources
to new leaf growth. However, at this time it is unclear how much
tree defoliation (premature leaf drop) must occur for yield
effects to justify the costs of management. For avocado growers
in Hawai’i, this ambiguity has led to the inefficient use of
various pesticide management programs and has resulted in further
economic losses, pesticide exposure to surrounding residential
and natural areas, and fragility in food security for the state.
Our project will investigate the association between tree
defoliation and avocado yield loss from accumulated ALB damage.
From these results, we will develop economic threshold models
that avocado growers will be able to use as management tools for
controlling ALB populations. These economic thresholds will be
based on initiating management programs when certain thresholds
of leaf damage across a tree are exceeded during a fruiting
season. We will conduct pesticide trials using these damage
thresholds and soil drenches of Admire®Pro (Bayer Crop Science)
to determine yield effects associated with varying degrees of ALB
damage. From these findings we will be able to derive economic
injury levels and develop threshold models for the Admire®Pro
soil drench program and several organic foliar spray programs.
From this project, we will improve stakeholder and grower
knowledge of how avocado lace bug (ALB) damage affects fruit
yield, what economic threshold models are and how they can be
used in management programs for ALB, and how basing management on
economic thresholds can help create a more sustainable
agricultural environment for Hawai’i. We will do this by (a)
conducting field demonstrations on monitoring ALB damage on-farm,
(b) summarizing ALB damage monitoring and economic thresholds
through accessible extension documents and scholarly articles,
(c) creating accessible online video demonstrating ALB life
history, damage monitoring, and economic threshold management,
and (d) disseminating project results at Hawai’i grower meetings.
We anticipate that results from this project will decrease
economic loss for avocado growers while also reducing pesticide
exposure to growers and surrounding residential/natural areas as
well as help maintain crop type diversity to aid in offsetting
food insecurity in Hawai’i. The management tools developed from
this project will be applicable to avocado growers in other
affected areas of the USA such as California, Florida, Texas, and
Puerto Rico.

Research Objectives:

• Determining an optimized subsampling method
• Conducting pesticide trials
• Examining proportion threshold effects on avocado fruit yield
• Developing an economic threshold model
• Developing economic threshold models for organic management
  programs

Educational Objectives:

• Conducting field demonstrations on monitoring ALB damage
• Summarizing ALB damage monitoring and economic thresholds
  through accessible extension documents and scholarly articles
• Creating accessible online video demonstrating ALB life
  history, damage monitoring, and economic threshold management
• Disseminating project results at Hawai’i grower meetings