2018 Crop Protection Guide for Tree Fruits in Washington

New Developments

Sunday, February 17, 2019

EPA Pollinator Protection web site

The Environmental Protection Agency (EPA) has proposed additional restrictions to protect bees used for commercial pollination, is encouraging states and tribes to develop pollinator protection plans, has developed new risk assessment guidance for pollinators, is using a bee hazard icon on pesticide labels as a quick guide that a pesticide contains special precautions or restrictions to protect pollinators, and is posting information on residual toxicity time to 25% bee mortality on their web site. For more information, please refer to the EPA Pollinator Protection web site at: http://www2.epa.gov/pollinator-protection


Spotted Wing Drosophila

We now have five years of experience in managing spotted wing drosophila (SWD) as a tree fruit pest in eastern Washington.  Cherries are our high-risk tree crop for SWD, and we can assume that SWD will play a role in our management programs in the future. Our years of experience with this pest indicate substantial year-to-year variation in pest pressure, possibly connected with severe winter cold events.  This provides an opportunity for omitting prophylactic sprays if pressure is low.  Our monitoring tools have improved over time also, and new synthetic lures appear to be more sensitive than the standard apple cider vinegar traps, hopefully providing us with early warning of impending damage.  However, action thresholds have not yet been established, and until this information is available, routine sprays are advised. Recommendations for cherries will be updated in on the SWD website at http://www.tfrec.wsu.edu/pages/swd/. General biology and monitoring information is available on the Orchard Pest Management Website.

Little Cherry Disease

There are a number of viruses inherent in sweet cherry trees in Washington.  Most of these viruses are of little consequence; however, there are a few viruses, including Little Cherry Disease, that are lethal to cherry trees and can spread from tree to tree through insect vectors or grafting.  The cool, wet spring of 2010 provided the perfect conditions for expression of these viruses in cherry trees throughout the state.  Cherry producers are advised to remain on alert for symptoms associated with Little Cherry Disease including branches with fruit that are smaller than normal, slow to ripen, somewhat pointed or triangular and with a bland or rather bitter flavor.  Foliage on affected trees may be lighter in color than normal trees, and growth may be somewhat reduced.  If these symptoms appear to be spreading from tree to tree from year to year, it would be prudent for growers to identify the cause of small fruit in their orchards. This may be done by contacting the Fruit Tree Clean Plant Network (FTCPN) at Washington State University ‐ IAREC, Prosser or your local WSU Extension Office.  The degree to which a crop is negatively impacted by these viruses will vary from year to year, depending on weather.  Infected trees are never as productive as healthy trees.  Immediate and proper removal of infected trees is imperative to prevent the spread of any lethal cherry viruses in your orchard and potentially to adjacent properties. More information about Little Cherry disease can be found at: treefruit.wsu.edu

New Information on Effects of Pesticides on Natural Enemies of Insects

We have always known that certain pesticides can disrupt natural enemy populations leading to secondary pest outbreaks, particularly of spider mites and aphids. Most of the information we have on the disruptive effects of pesticides comes from studies that assess the direct impact of a pesticide on natural enemy survival when they are exposed to sprays or to residues.  These impacts are typically recorded as the percent of natural enemies dying in 24 or 48 hours.  However, we have learned that sub-lethal effects, usually a negative impact on reproduction by sterilizing adults or reducing the number of viable eggs laid, can lead to decreases in natural enemy populations and cause or contribute to outbreaks of pests. Sub-lethal effects are more subtle than acute effects but can result in large decreases in population size.  A recently completed Specialty Crop Research Initiative Project developed information on the impact of several pesticides on a select group of natural enemies, including how sub-lethal effects impact natural enemy reproduction.  This information can be found on the project’s web site at EnhancedBiocontrol.org.  The table presented on this web site shows what would be the reduction of a natural enemies population growth due to acute or sub-lethal effects if exposed to the different pesticides tested.  The information from this project has been incorporated into the Natural Enemy Effects table in this publication. 

Endosulfan phase-out

Endosulfan was the subject of a voluntary cancellation as part of the endosulfan Memorandum of Agreement (MOA) between EPA and registrants on 7/22/2010. All endosulfan registrations will be canceled over a six-year phase-out period (2010-2016). Part of the MOA included specific existing stocks provisions that must be included on revised endosulfan labels. Crops were divided up into six groups for the phase-out.

It became unlawful to use the product on sweet cherries, peaches and nectarines as of July 31, 2012.

It became unlawful to use this product on pears after July 31, 2013.

It became unlawful to use this product on apples after July 31, 2015.

Voluntary Cancelation of thiacloprid (Calypso)

All U.S. thiacloprid registrations have been voluntarily cancelled by the registrant. Calypso products in the channels of trade can be sold and distributed until Feb 8, 2016. Growers with existing stocks may continue to use product in the labelled manner until those existing stocks are gone or tolerance is revoked, whichever comes first.

Tree Fruit Research & Extension Center, 1100 N Western Ave, Washington State University, Wenatchee WA 98801, 509-663-8181, Contact Us