Be on the Lookout for Pest Problems in 2018

Q&A with Brett Blaauw, PhD, on Managing Pests in the Orchard this Year

by TERESA SCHIFFER

Every year presents new challenges when it comes to managing pests in the orchards. We asked
Brett Blaauw, PhD, Assistant Professor and Extension Specialist at the University of Georgia’s
Entomology Department, for some insight as to what creatures orchardists in the Southeast should be
on the lookout for this year.

The Peach News (TPN): Q: What pests do you anticipate being big problems in 2018?

Brett Blaauw, PhD: Scale insects, such as San Jose scale and/or white peach scale. Also, borers,
particularly lesser peach tree borer.The Peach News (TPN): What pests do you anticipate being big problems in 2018?
Brett Blaauw, PhD: Scale insects, such as San Jose scale and/or white peach scale. Also, borers,
particularly lesser peach tree borer.

The Peach News (TPN): Q: How will this differ from past years?

Blaauw: San Jose scale has been increasing in abundance and severity over the past decade and does
not seem to be slowing down. On top of that, with last year’s widespread crop loss, insect pest
management in orchards with severe crop loss was likely neglected or reduced. Such a reduction may
have allowed scale abundance to grow throughout the season, resulting in considerably larger scale
populations this spring than typically anticipated. Similarly, seasonal cover sprays help suppress lesser
peach tree borer populations within orchards, and thus a reduction in these insecticide applications last
year may have resulted in an increase in borer infestations.

The Peach News (TPN): Q:What effects could these pests have on harvests?

Blaauw: Both scale insects and lesser peach tree borer are considered indirect pests of peaches,
meaning they attack the tree rather than the fruit. The significant injury due to scale can lead to twig or
limb die-back, even death of trees if populations reach high levels. Although considered an indirect
pest, at high populations, scale can move to the fruit, resulting in small, red, measle-like lesions on the
peach skin.
Orchards heavily infested by lesser peach tree borer suffer reduced fruit size and yield.
Continued attack by these borers can result in premature tree decline and death. Thus, high infestations
of either of these pests has the potential to considerably reduce yield and the overall lifetime of an
orchard.

The Peach News (TPN): Q: What do farmers need to do to prepare for these possibilities?

Blaauw: For scale insects, infested branches and limbs should be pruned out and removed/destroyed.
Since pruning is required anyway, targeting scale infested branches can significantly reduce the scale
population within an orchard. Growers also need to apply horticultural oil as a dormant and as a
delayed-dormant application to every acre of peaches, every year. Coverage with the oil is crucial for effective scale control. The addition of an insecticide (i.e. chlorpyrifos or an insect grower regulator) with the delayed-dormant application can improve early season control of scale. Additional applications of insecticides later in the season may be needed if populations continue to grow. The most effective lesser peach tree borer control programs rely on a combination of a preventative chlorpyrifos spray applied at delayed-dormant, followed by a full-season cover spray
program.

The Peach News (TPN): Q: How would organic farmers need to handle the pests?

Blaauw: Similar to the conventional grower recommendations, organic management of scale relies on
pruning and horticultural oils. In this case, growers need to apply an OMRI approved horticultural oil as
a dormant and as a delayed-dormant application to every acre of peaches, every year.
Organic options for lesser peach tree borer are limited. Applications of an organic pyrethroid
(i.e. pyrethrum) throughout the season may help suppress borer populations. Additionally, a new
mating disruption formulation for the Southeast has been developed, tested, and now registered for GA
and SC. While the results are highly encouraging, for the most effective control of borers, mating
disruption needs to me implemented on a large-scale area of peaches.
Lesser peach tree borers need rough surface, such as cracked or peeling bark, to lay their eggs
on, so for both organic and conventional growers, it is important to keep the trees healthy and the bark
intact. That can significantly reduce the chances of borer infestations.

The Peach News (TPN): Q:  In economic terms, what impact will these pests have as compared to other years?

Blaauw: This is really hard to predict. I sure hope this is not the case, but if scale insects and/or borers
went unchecked/unmanaged in 2017, the loss in scaffold limbs or trees could be substantially higher in
2018 compared to previous years.

The Peach News (TPN): Q: What is your advice for growers experiencing pest problems in their orchards?

Blaauw: Contact their local extension agents and/or state specialists. Additionally, the “Southeastern
peach, nectarine and plum pest management and culture guide” and the MyIPM smartphone
application are excellent and informative resources.
While I have focused on two major pests of concern, it will be important to keep an eye on plum
curculio and sap beetles, especially in orchards with a previous history of issues with these pests. And of
course, the diseases are a whole other ongoing issue that producers will continue to deal with in 2018.