Posts Tagged: blueberry
Brake On! A New Herbicide in Highbush Blueberry
Brake On! is a preemergence herbicide registered in blueberry and other horticultural crops in...
Beneficial Wasp Coming Our Way?
Kym Pokorny - Oregon State University
Destructive Pest of Cherry, Grapes, Peaches, Blueberry, Fig and
Lots of Other Fruit
to Come Under Wasp Control?
Corvallis, Ore., June 6, 2022– After 12 years of research, a parasitic wasp that controls a highly destructive fruit fly will be released by Oregon State University agricultural scientists in June.
Vaughn Walton, Extension entomologist and professor in the College of Agricultural Sciences, said the U.S. Department of Agriculture has permitted release of the wasp (Ganaspis brasiliensis), a slow process that took more than 10 years from application to decision. Now that it has a permit, Walton's lab, which is part of the OSU Agricultural Experiment Station, is raising enough wasps to make a dent in the spotted wing drosophila (SWD, Drosophila Suzuki) population in Oregon.
“This will have a huge impact,” Walton said. “Spotted wing drosophila is very difficult to control. It's got a very, very high reproduction rate with many generations per year. Because of that, when using pesticides, they have to be applied constantly, sometimes two or three times a week. Growers are really interested and are excited about a biological control that will work along with cultural management tools to decrease SWD and not cost them any money. It's a natural resource available to them. We think this is going to change things.”
A holistic integrated pest management (IPM) approach that uses cultural controls like good sanitation, proper pruning, drip irrigation and weed cloth can be somewhat effective. But IPM management programs still need the addition of pesticides to fight spotted wing drosophila, Walton said.
Spotted wing drosophila, a tiny fruit fly that resembles those that hover over rotting fruit in summer, is well suited to the Willamette Valley climate. About 95% live in areas surrounding non-crop habitats that act as pest reservoirs for reinvasion of the crops. That's where the wasp will be released.
The adult female fly lays her eggs — up to 600 per year — within ripening fruit, said Ryan Chave, a graduate student who works with Walton. When the larvae emerge, they burrow in and start eating the fruit from the inside out, causing damage that results in severe crop losses.
The parasitoid wasp kills SWD by laying eggs inside the insect and when the wasp hatches, its larva consumes its prey, Chave said. Spotted wing drosophila populations can be kept at a bay at a rate of up to 65% when the parasitoid wasp is there to check it, according to preliminary data.
“We'll never take down the entire fly population,” Walton said. “But as SWD increases there's more food for the wasp. In the field if you have a bunch of SWD attack a crop and reproduce, as they increase there it gets larger and larger.”
Though not native to Oregon, a few of the parasitoid wasps were found in Oregon and allowed the researchers an opportunity to study them in the field. They're confident it will not become an invasive pest problem since G. brasiliensis is a specialist — in other words it only feeds on SWD, said Walton, who worked closely with Jana Lee of the Oregon Department of Agriculture. He also collaborated with colleagues at University of California, Berkeley. Walton has studied another Asian wasp (Pachycrepoideus vindemmiae) that has promise but not as much as G. brasiliensis because it's a generalist and will kill other insects in addition to spotted wing drosophila.
G. brasiliensis image: Dr. Kent Daane (University of California, Berkeley)
/span>Something is Different This Year
Plants have been acting differently this spring. Along the coast the peaches have barely bloomed and it's May. Avocado Brown Mite has had a field day. Stethorus beetles have been in low numbers and biocontrol is out of whack.
Her ladybug Coccinelid sisters have been in low numbers, as well. There's lots of ladybug species in the coastal area. Usually the first ladybugs show up on the aphids feeding on the malva (cheeseweed) new growth. I haven't seen many aphids on the malva, but for the last several weeks the new growth on citrus has been hammered by green peach aphid (http://ipm.ucanr.edu/PMG/r604300111.html). They have also been feeding on new growth blueberry.
This aphid doesn't normally get out of hand like this. Possibly the fires have burned up the hills where they were hibernating this winter? Aphids are not normally a problem in either mature citrus or blueberry. It can run it's course, and something will come in to eat them, but it's interesting how a year can be so different from others.
More winter stories
//ucanr.edu/blogs/blogcore/postdetail.cfm?postnum=26823
green peach aphid
Blueberry Gall Midge?
Several Florida blueberry growers have recently reported flower bud damage and corresponding fruit loss, in some cases up to 50% on certain affected cultivars. These reports have focused primarily on Emerald, Farthing and Meadowlark, although other cultivars may have also been affected to some degree. There could be multiple reasons for flower bud damage and the resulting fruit loss, including hydrogen cyanamide and freeze damage. However, in several cases this year it is believed that this type of damage has been caused by blueberry gall midge.
High populations of blueberry gall midge in blueberry can result in significant flower bud injury and reduce fruit set and yield. Females lay eggs in floral and vegetative buds just after bud swell. Gall midge larvae then feed on developing leaf and floral buds. Affected floral buds develop a dry, shriveled appearance and will often disintegrate (Figure 1). Damaged leaf buds are characterized by misshapen leaves and blackened and distorted shoot tips (Figure 2). When the terminal bud on a shoot is injured or killed, shoot elongation growth may be inhibited with excessive later branching occurring just below the damage terminal bud. Weather may impact the density of gall midge populations, with warmer temperatures > 60o F resulting in early emergence. Furthermore, re-infestation of previously infested areas is common if management action is not taken when gall midge injury is observed.
Growers should be aware of the possibility of gall midge damage in their fields this season, resulting in floral bud death and lower fruit set. Dr. Oscar Liburd, University of Florida blueberry entomologist, is preparing a bulletin to be released very soon with current gall midge management recommendations to be implemented after this season's harvest is complete. Until this extension bulletin is ready to be published, growers can view pesticide recommendations for gall midge in The Blueberry News magazine.
High populations of blueberry gall midge can result in significant flower bud injury and reduce fruit set and yield, Phillips points out. The following are his scouting tips for this pest.
![Blueberry gall midge bud damage](http://files.growingproduce.com/growingproduce/wp-content/uploads/2014/09/blueberry_gallmidge_bud_damage.jpg)
Blueberry gall midge bud damage
Photo by Craig Roubos
- Females lay eggs in floral and vegetative buds just after bud swell. Gall midge larvae then feed on developing leaf and floral buds. Affected floral buds develop a dry, shriveled appearance and will often disintegrate.
![](http://files.growingproduce.com/growingproduce/wp-content/uploads/2014/09/blueberrygallmidge_leafdamage.jpg)
Symptoms of blueberry gall midge leaf damage
Photo by Craig Roubos
- Damaged leaf buds are characterized by misshapen leaves and blackened and distorted shoot tips. When the terminal bud on a shoot is injured or killed, shoot elongation growth may be inhibited with excessive later branching occurring just below the damage terminal bud. Weather may impact the density of gall midge populations, with warmer temperatures (greater than 60°F) resulting in early emergence. Furthermore, re-infestation of previously infested areas is common if management action is not taken when gall midge injury is observed.
Is this something that California growers should be concerned about? To my knowledge these midges have not been reported in California. We also don't use hydrogen cyanamide which may be contributing to the problem. With plant material and people moving around, though, it might show up and be a problem. I never thought blueberry rust would show up in California, but as the crop has become more widespread, it has showed up. Ever alert.
Alert from UF/IFAS Blueberry Extension Coordinator Doug Phillips:
http://entnemdept.ufl.edu/creatures/fruit/blueberry_gall_midge.htm
https://pubag.nal.usda.gov/download/10784/PDF
Photo: Blueberry Gall Midge, Dasineura oxycoccana
blueberry gall midge
Disaster Contacts for Growers
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