| Today Pistachio growers heard from David Haviland about Gill's Mealybug|
pressure and control timing.
Gill’s Mealybug Field Meeting
Focuses On Damage and Treatments
By Patrick Cavanaugh, Editor
Today, pistachio growers, PCA
and others gathered in a Tulare County Pistachio orchard owned by Dennis Burner
who is cooperating in a Gill’s mealybug control trial with UC Farm Advisors.
Attendees saw mealybug pressure on trees and heard about the best time to treat
for the pest.
Gill’s mealybug is a relatively
new pest of pistachios in California. “It was first recognized in the late
1990s in a an orchard near Tulare. It has now spread up to Colusa County and
has move down to Kern County,” said David Haviland, UC Cooperative Extension
Kern County, who organized the field day with Elizabeth Fichtner, UC
Cooperative Extension Tulare County.
Tulare County is a hot spot
with most pistachio orchards having the bug, which has three generations per
year. “Right about harvest time there are a whole bunch of mealybug crawlers
hatching, and then they overwinter and become adults in May. These adults will
produce an enormous amount of new crawlers the first week of June, which is an
important treatment time, right when those crawlers come out,” said Haviland. “The
ones that are born the first week of June will become adults in about mid-to-late
July, which is the second generation. The mealybugs that are in the tree now
are the start of the third generation when they become adults then hatch more
young bugs at harvest.”
will get millions of crawlers at harvest, but if you come back to the tree in
the spring, you will see maybe one or two per pistachio cluster, so there is a
huge winter mortality,” said Haviland.
Haviland stood by a tree that
had only about one mealybug per 10 clusters in the May, but now the untreated
trees in the trial have clusters that are covered with honeydew, and now
blackened with sooty mold, with 30 or 40 adults on the clusters. The lower
leaves on the trees were turning black from the sooty mold.
|Gill's Mealybug on pistachio clusters|
Causing a sooty mold mess.
“Typically growers go out in
their orchards April and May and see about one mealybug for every 10 clusters.
In fact they might not even notice it. But that mealy bug produces about 20
live young, which increases the count to about one per cluster, but now those
adults give rise to 15 or 20 crawlers per cluster which causes clusters to be
moist and black,” said Haviland. “So the point is that one or two per cluster
can cause many more per cluster near harvest time, so May is the time to be
thinking about spraying the first of June.”
Haviland looked back at the
tree he was standing next to, and said: “If you have tree that looks like this,
with a lot of mealybugs and sooty mold, let it go; you can’t do anything about
it. Come back the first week of June 2014 and treat it with an insecticide and
you should be clean at harvest next year. It’s really that simple.
Insecticide timing is
important, but there is a widow. Of all the products registered, they are most
effective on crawlers. “So you really want to get them the first week of June
when the crawlers are out regardless of which product your using,” Haviland
During the upcoming harvest
season, Haviland warn growers to ask the harvest crew to wash down the
harvesting equipment and make sure no tree debris from another orchard is on
the equipment. “And if growers have an orchard with mealybug, please inform the
harvest crews so that they clean the equipment before moving to another site,
which may not have mealybug.
“The harvest crew should blow
off all leaf trash and hose the equipment down before it goes from property to
property. Growers should insist upon this,” Haviland said.
Labels: David Haviland, Dennis Burner, Gill's Mealybug Field Meeting in Tulare, UC Farm Advisor Kern County. Pistachio growers