In Albany County on June 19, 2017, traps checked at a summer raspberry planting had 8 SWD, 1 female and 4 males in traps on the edge and 1 female and 2 males in traps within the crop. This farm site has a U-pick strawberry field adjacent to the raspberries, as well as a blueberry planting. SWD management at this location relies on sanitation - picking fruit heavily: clean picking and removing unmarketable fruit from the planting.
A typical pattern of SWD monitoring in June strawberries has been that little to no SWD are found, either in traps set in June strawberries or infesting June strawberries, which may not be an optimal host. When June strawberries are mowed after harvest, SWD shows up in raspberry traps set in plantings adjacent to the strawberries.
Because of early SWD arrival this year and optimal weather conditions for SWD—warm, wet, and cloudy—it is advisable to monitor your June strawberry crop and practice clean picking. More on SWD management is on Cornell Fruit ResourcesSWD pages.
In Niagara County during the week ending June 21, 2017, 2 SWD females were caught in traps set in a blueberry planting both within and on the edge of the crop. In addition, 1 female was caught this week at another site in Niagara County in a trap set within a red raspberry planting. There are four traps at each of these locations. These are the first SWD caught this season in this county. These traps are being monitored by Tess Grasswitz, IPM Specialist on the Lake Ontario Fruit Program, Cornell Cooperative Extension.
The blueberries and raspberries at these sites are not ripe. The red raspberries are starting to show color, but are still hard. The focus now should be on opening up the canopy, maintaining weed control, and mowing row middles and field edges. These tactics will improve air circulation, sunlight penetration, and improve insecticide spray deposition on fruit for when your insecticide spray program begins. More on SWD management is on Cornell Fruit Resources SWD pages.
There were 3 females found on June 20, 2017 in one of four traps set in summer raspberries in Schuyler County. The trap was set within the planting and the fruit are ripening. The risk of SWD infestation to summer fruit will likely be significant this year. Four traps set in an adjacent blueberry planting where the fruit are still green caught no SWD.
These traps are being checked weekly by Nicole Mattoon and Taylere Herrmann who work with Juliet Carroll, Fruit IPM Coordinator, NYS IPM Program, Cornell Cooperative Extension.
It is time to think strategically about all the management practices that can thwart this invasive pest. Use several tactics. Manage weeds and mow row middles. Protect the crop with insecticides. Use sanitation. Maintain a cold chain to slow or stop development of SWD in fruit.
For summer raspberries - in July, prune out the smallest primocanes, beginning when they are 12 to 18 inches high to select and keep the biggest and best canes for next year. Begin removing spent floricanes in July along with any late emerging primocanes. Maintain 4 or 5 healthy floricanes per foot of row.
One female SWD was found on June 14, 2017 in a blueberry planting. Four traps were set at this location on June 7 and one of the two within the planting caught the female. The blueberries at this location are green and lingering bloom was still evident on some plants this week.
These traps are being monitored by Nicole Mattoon, field technician, and Taylere Herrmann, summer technician, in Juliet Carroll's fruit IPM program with the NYS IPM Program.
Single SWD were found at two monitoring locations in Tioga County. One female on June 13, 2017 in a trap set outside of a raspberry high tunnel planting. One male, also on June 13, 2017 in a trap set within a fall raspberry field. The traps were set on June 8 and are being monitored by Margaret Ball, extension educator, Tioga County Cornell Cooperative Extension.
The pattern of SWD population buildup is typically slow to start, with exponential growth in mid- to late summer. Low level infestations of SWD are difficult to spot. Fruit that is ripe and ripening at this time includes strawberries, day neutral and June bearing, sweet cherries and early maturing blueberries. Of these I'm only aware of strawberries being harvested at this time.
Make sure to scout your susceptible fruit crops for symptoms and signs of SWD infestation and take routine samples of fruit to check for larvae with salt flotation. The Spotted Wing Drosophila pages in Cornell Fruit Resources have more information on SWD, including tips on management.
A single male SWD was caught in a trap placed at the edge of a blackberry planting in an orchard in Saratoga County, during the week ending on June 13, 2017 .
This was one of 4 traps being monitored at this site (the other three traps caught no SWD). The report comes in from Annie Mills, field technician with Laura McDermott, extension educator with the Eastern NY Commercial Fruit Program.
There was a raspberry planting nearby in previous years. This was taken out and new raspberries were planted next to the blackberry planting. No fruit on the raspberries yet and the blackberries are currently still in bloom.
To protect crops from SWD infestation, once susceptible fruit is ripe and SWD is in your area, manage them aggressively. Using a combination of tactics is better than relying on one; and is the foundation of integrated pest management (IPM). Talk to your local Extension office about how to monitor for SWD, read Extension newsletters and alerts, and know your crops’ growth stages. When adult SWD are present on your farm AND fruit are ripening, it is time to protect fruit and reduce SWD population growth with insecticides, unless exclusion netting is in place.
Raspberries, blackberries, and blueberries are at high risk of SWD infestation. Fall-bearing and late maturing varieties are at far greater risk than early maturing ones, because SWD populations build exponentially to very high levels in late summer and early fall. June-bearing strawberries may escape injury, whereas late summer fruit or day-neutral varieties may suffer damage. Cherries, both tart and sweet, elderberries, peaches and plums are also susceptible, but harvests may occur before SWD populations buildup. Thin-skinned grapes can be infested directly, though cracked or damaged berries are more susceptible.
Female SWD can lay eggs directly into sound fruit. They prefer ripe fruit, but can lay eggs in fruit even as ripening begins. Therefore, keep an eye on fruit development in your fields. Egg laying activity is greater under conditions of low light, such as dawn and dusk or in dense plant canopies, weed-shaded areas in a planting, or parts of the planting shaded by adjacent woods or buildings. Adult SWD, in general, are most active during cool, humid times of the day. We have had significantly cool and moist weather this spring and first catch of SWD has occurred in a few areas in NY already.
Examine your plantings for conditions that promote SWD infestation and take steps to eliminate them. Although we cannot change the weather, we can alter conditions in the planting to reduce the cool, dark, humid areas preferred by SWD. Canopy, weed and irrigation management will make the environment less favorable. If your fruit planting lends itself to full enclosure, consider exclusion netting to keep SWD out.
Canopy - Pruning and training systems must maintain an open canopy to increase sunlight and reduce humidity. This will make plantings less attractive to SWD, will reduce SWD activity and will improve spray penetration and coverage. Added benefits include improved fruit color and flavor promoted by sunlight, easier picking by workers and customers, and easier weed management. Pruning tactics have been developed to achieve excellent fruit yield and open the canopy. I will detail these in a later blog. Although the best time to prune is over, knowing different strategies now will help you in the future.
Weeds - Mow row middles and field edges routinely to reduce preferred habitat for SWD within and around the planting. Eliminate weeds within rows to increase sunlight penetration into the canopy, reduce preferred habitat, and improve spray penetration into and deposition on the canopy.
Irrigation - Repair leaking drip lines and avoid overhead irrigation when possible. Allow the ground and mulch surface to dry before irrigating. Eliminate problem areas where water puddles are slow to dry out. Raised beds are essential for raspberry production to reduce Phytophthora root and crown rot and will also help maintain a dry environment under the planting.
As fruit begins to ripen, know if SWD has been found in your area. If you are monitoring SWD with your own traps, check them routinely. If feasible, check them daily. It is easier to sort through a small number of vinegar flies caught in traps to look for SWD than it is to sort through 40-400. Females usually arrive first, but males are soon to follow and often caught along with females.
If SWD is in your area and susceptible fruit is just about ripe, insecticide treatments could begin. This will be especially true in years when SWD arrives early, because SWD populations will build to high levels placing even summer-maturing fruits at risk, particularly when weather conditions are ideal for SWD activity—cloudy, cool, moist. When SWD populations are high, treatments should be applied every five to seven days and repeated in the event of rain. Choose the most effective insecticides with pre harvest intervals that work for your picking schedule. Rotate insecticides according to their modes of action to prevent the development of insecticide resistance. Insecticide sprays will kill or suppress SWD adults, thereby reducing egg laying and slowing population buildup.
Resistance management – Insects treated with the same pesticide repeatedly may develop resistance to that pesticide’s mode of action. The Insecticide Resistance Action Committee (IRAC) has developed groupings for modes of action. When materials in one IRAC group are used exclusively over an entire growing season and over years, they are at high risk of becoming worthless as a control measure due to resistance development. Always rotate between IRAC groups, as described on the label.
Protecting pollinators – If your crop is flowering, that means there are pollinators visiting flowers. Therefore, spraying insecticides will place pollinators at risk of non-target exposure to insecticides, unless these materials are applied when pollinators aren’t active, such as during dawn or dusk, or when the crop is no longer flowering. This can be particularly challenging for raspberries and blackberries, which may have a long bloom period that spans fruit ripening. Organic-approved products with the active ingredients spinosad, azadirachtin, and pyrethrum are toxic to pollinators. No matter which insecticide you choose, always read the label and keep pollinators safe from insecticide exposure.
Regularly inspect fruit in the planting for symptoms and signs, paying close attention to fruit ripening in areas prone to SWD activity—near woods, shaded or wet areas—span a random transect of the planting. Sample ripe fruit and examine it microscopically for egg breathing tubes or check for larvae with salt flotation. Get infested fruit out of the planting so SWD populations don't have a chance to buildup.
Symptoms - Fruit can be inspected for evidence of larval feeding. Small holes in berries where the eggs were laid may leak juice when the berry is gently squeezed; this is especially diagnostic on blueberry, cherry, and plum. Infested red raspberry fruit may leave a red juice stain on the berry receptacle when the fruit is picked. Fruit with small indents or bruises where the berry surface appears to have flattened or deflated may be damaged. Help with identifying symptoms is found in the fact sheet, Recognize Fruit Damage from Spotted Wing Drosophila (SWD), from Oregon State University.
Breathing tubes - Egg breathing tubes are two tiny, evanescent, white hairs attached to the egg laid just below the fruit skin. In blackberry, grape, blueberry and cherry it may be relatively easy, though tedious, to find these on fruit in which eggs have been laid, but magnification is essential. A 20x hand lens or loop or a dissecting microscope is needed, and patience. Examine the entire fruit surface. Fuzzy fruit, such as raspberry, are harder to examine because of the difficulty distinguishing breathing tubes from normal plant hairs. To confound the inspection, once eggs hatch, the breathing tubes fall off. You may be able to train your eye to see SWD egg breathing tubes.
Sample fruit - Salt flotation can be used effectively to keep records of infestation levels in your harvests. At least 100 fruit per block per harvest should be observed for infestation. Immerse fruit in a solution of 1 Tbsp. (14.8 cc) table salt per 1 cup (236.6 ml) water. The salt solution causes larvae to move out of fruit and float into the salt solution. Suggested methods were adapted for NY growers by Laura McDermott in Guidelines for Checking Fruit for SWD Larvae in the Field (pdf).
Sanitation - Excellent sanitation will reduce SWD populations. Fruit should be harvested frequently and completely to prevent the buildup of ripe and over-ripe fruit. Unmarketable fruit should be removed from the field and either frozen, "baked" in clear plastic bags placed in the sun, or disposed of in bags off-site. This will kill larvae, remove them from your crop, and prevent them from emerging as adults.
Protect your harvests and customer base. Pick only the best and perhaps still slightly firm fruit to help them last longer in your markets. Chilling fruit after harvest is an essential step in prolonging shelf life. Picking crews can pick overripe or suspect fruit into a separate container to get them out of the field. Although the larvae of SWD are safe to eat, most people won’t want to do so. Informing customers about SWD and making sure they refrigerate fruit once home will help them understand how to deal with this invasive insect, and still benefit from eating nutritious and delicious fresh fruit.
Cool berries - Chilling berries immediately after harvest to 32° - 33° F will slow or stop the development of larvae and eggs inside the fruit. U-Pick customers should be encouraged to follow this strategy to improve fruit quality at home.
Proactive – Be proactive with your customers. Let them know that you are doing everything you can to manage SWD in your fruit crops. Inform them about refrigerating or freezing fruit as soon as they get home. Highest quality of preserves, jams and jellies will be achieved if prepared soon after purchase.
The take home message for SWD management—use a combination of tactics, choose IPM.
On June 6, 2017 one female SWD was identified in a monitoring network trap set last week in the wild shrubs at the edge of a red raspberry planting in Orleans County. This report is coming in from Tess Grasswitz, entomologist and educator with the Lake Ontario Fruit Regional Extension Program. She checked another set of SWD traps in raspberries and one set in blueberries (both in Niagara county), which were negative for SWD.
Stay tuned and stay prepared.
Insecticide sprays are not warranted unless fruit is ripe. Please keep close watch on June strawberries this year, as it appears to be an early year for SWD and a slow year for crop development, which may place this crop at risk. More on SWD management coming soon.
On June 7, 2017, 3 female and 1 male SWD were identified in a monitoring network trap set on June 1st in the border row near the wooded edge of a blueberry planting in Suffolk County. The other trap inside the same blueberry field, as well as traps in other locations (raspberry, blackberry, and grape) did not catch any SWD. This is the first catch in Suffolk County, Long Island in this season. Faruque Zaman, entomologist and educator with Suffolk County Cornell Cooperative Extension and the Long Island Horticultural Research and Extension Center sent in this report.
A comprehensive blog on SWD management will be posted today, also. In most locations in New York, raspberries are beginning to flower, blueberries have just set fruit, and June strawberries are just beginning to ripen.
Monitoring of SWD in New York has begun! Twelve Cornell Cooperative Extension programs and 13 extension scientists are cooperating this year. Some research sites may also be included in the mix, courtesy of the programs of Greg Loeb at the NY State Agricultural Experiment Station in Geneva, NY and Peter Jentsch at the Hudson Valley Laboratory in Highland, NY. Below are listed the Extension personnel who are monitoring SWD in New York in 2017.
Traps will be set in 21 counties. Based on research results comparing various lures, we are using the Scentry trap and lure for our monitoring network, as we did in 2016. We’ll post trap catch reports to this blog and enter them into the SWD distribution map.
Our Cornell Fruit Resources website is being launched in a new format and location this week. We are doing our best to redirect you to those resources from within the new site. Some of those pages contain SWD information. As that information is revised for 2017, I’ll post it on the SWD blog and include the new link.
Reports of early trap catch this year are coming in from Michigan. However, fruit is not susceptible until it is close to fully ripe. Currently, June strawberry fruit is green, early blueberries have just set fruit and raspberries are just starting to bloom. No risk of SWD infestation at this time.
Growers interested in monitoring for SWD in their berry plantings can contact me for information and tips, Juliet Carroll, Fruit IPM Coordinator, firstname.lastname@example.org.
My upcoming blog will be a review of IPM tactics for SWD in berries. Stay tuned and stay prepared.