Rust Mites Can Cause Damage Shortly After Budbreak

Dr. Patty Skinkis, Viticulture Extension Specialist & Associate Professor

Grape rust mites have been a nuisance pest in vineyards of western Oregon for years. They can be found living on grape tissues from early spring through summer. Grape rust mite has been known to cause shoot deformity early in the growing season with most notable damage in years when vines have delayed growth under cool conditions.

Being aware of the first signs and symptoms of rust mite infestation in early spring is important to determine if there is a problem. However, visual symptoms are not enough for action. It is critical to determine presence of grape rust mites before considering application of miticide sprays. The presence of high numbers of rust mites have been found to cause severe stunting of emerging buds and  young shoots. For examples of these symptoms, see the grape rust mite section of the PNW Insect Management Handbook. There can be numerous other causes of stunted shoots, but with the hype of rust mite concerns, many growers blamed rust mites as the cause of all stunted shoots. As a result, there have been potentially unnecessary applications of miticides (sulfur, lime sulfur, stylet oil, or other miticide products) early in the season.

Grape rust mites are impossible to see with the naked eye, so tissue collection and viewing under magnification is required. A user-friendly method was recently developed by a team at the OWRI to monitor grape rust mites on vine tissues. This method has since been employed by growers in Oregon to determine presence of rust mites. The protocol is available for use and links provided below:

Using this method, we were able to determine a strong correlation of rust mite presence on stunted shoots early in the season. Damaged shoots often had hundreds of mites; there were over 100 mites found on shoots <10 cm in length using the rinse in bag protocol and up to 500 mites when evaluated upon subsequent extractions (Schreiner et al. 2014). Since there can be great variability in mite numbers and rapid growth of tissues early season, it is difficult to determine clear action thresholds. However, action is warranted if there is significant shoot stunting, deformity and confirmed high populations of rust mites. In-season sulfur sprays that are applied as a means to prevent powdery mildew has been found to keep rust mite populations in check (Schreiner et al. 2014). Current recommendations exist for early season rust mite control, and those can be found in the 2015 Pest Management Guide for Wine Grapes in Oregon.

For more information about monitoring for rust mites and management, see the following publications and resources:

Schreiner, R.P., P.A. Skinkis, and A.J. Dreves. 2014. A rapid method to assess grape rust mites on leaves and observations from case studies in Western Oregon vineyards. HortTechnology. 24: 38-47.

Skinkis, P.A., J.W. Pscheidt, E. Peachey, A.J. Dreves, V.M. Walton, I. Zasada, R. Martin, D. Sanchez, and C. Kaiser. 2015. 2015 Pest Management Guide for Wine Grapes in Oregon. OSU Extension Publishing.  https://catalog.extension.oregonstate.edu/sites/catalog.extension.oregonstate.edu/files/project/pdf/em8413_0.pdf

Skinkis, P. 2014. Grape Rust Mites, eXtension/eViticulture.org. http://www.extension.org/pages/33107/grape-rust-mite#.U_yZCHcXOVo

Skinkis, P., J. DeFrancesco, and V. Walton. 2015. Grape Rust Mite, PNW Insect Management Handbook. http://insect.pnwhandbooks.org/small-fruit/grape/grape-grape-rust-mite

Dr. Vaughn Walton, Associate Professor, Department of Horticulture, Dr. Nik Wiman, Assistant Professor Sr. Research, Department of Horticulture, OSU, Daniel Dalton, Faculty Research Assistant, Department of Horticulture, OSU

Brown Marmorated Stink Bug, (BMSB) is an invasive pest that has spread significantly throughout Oregon’s Willamette Valley. Since 2012, BMSB has increasingly been encountered by growers and can be found in wine grape vineyards of the Willamette Valley during the harvest period (Wiman et al. 2014), and established populations of BMSB are now found within the boundaries of nearly all Oregon AVAs. The highest risk areas include the Chehalem Mountains, Dundee Hills, Eola-Amity Hills, and McMinnville AVAs, although the risk is also increasing in AVAs located in southern Oregon and the Columbia Gorge. BMSB feed on vegetative tissues and grape berries, potentially causing contamination of wine grapes and wine quality losses.  BMSB may be moving into wine grapes late in the season because other food sources become unavailable and population levels are at their peak. BMSB also display “hilltopping” behavior in the fall, where they may aggregate at relatively high elevations for overwintering. Unfortunately, this means they will encounter vineyards and wineries. Winemakers have reported infestation of winery buildings and finding dead BMSB in fermenting wines.

Brown Marmorated Stink Bug can develop on a wide range of host plants, meaning that it can find refuge or reproduce on non-crop hosts and then spread to cultivated crops such as wine grapes. Often, BMSB can be found along vineyard borders that have host plants such as bigleaf maple, Himalayan blackberry, Oregon ash, or other species that produce abundant seeds or fruits. Fruit feeding by adult BMSB may cause direct crop loss due to berry necrosis (VMW, SCRI CAP grant report 2013). Contamination of grape clusters and taint because of BMSB defense chemicals is also concern. These taints can be persistent, and may result in market losses. Work conducted on Pinot noir has shown that trans-2-decenal, a defense compound produced by BMSB, is a contaminant present in wine that is processed with BMSB.

Populations of BMSB have continued to grow unabated, with major increases over the past two seasons because of increased distribution and long growing seasons. The extra heat units during the growing season allow more of the nymphs to reach the adult stage and then fly to overwintering sites. Furthermore, lack of cold temperatures in winter has limited mortality. BMSB pressure is predicted to increase in 2015 over levels seen during 2014. Growers are encouraged to learn to recognize BMSB to be aware of potential damage or contamination risk during the harvest season. BMSB can be scouted by visual observation of clusters with efforts concentrated on borders. Despite availability of commercial products, traps are not encouraged at this time because of lack standard monitoring protocols and inability to link trap captures to meaningful damage thresholds.

 Spotted Wing Drosophila, Drosophila suzukii (SWD), is firmly established in most Oregon vineyards (Loriatti et al. 2015). D. suzukii contributes to spoilage of wine grapes, but only under certain conditions. Our studies have shown that wine grapes are less suitable than fresh berry crops as a reproductive host for SWD. Wine grapes damaged by pre-harvest rains, birds or fungal infection are attractive to SWD, and when high population levels coincide with split grapes, SWD can affect quality of wine grapes by acting as a vector of Acetobacter spoilage bacteria.

The lack of winterkill and seasonal population models indicate that SWD will be present at high levels during harvest in 2015.  Growers should be aware that conditions suitable for vectoring of spoilage bacteria may result in an economic impact by SWD during harvest of 2015.

References

Ioriatti C., V. Walton, D. Dalton, G. Anfora, A. Grassi, S. Maistri and V. Mazzoni. 2015.  Drosophila suzukii (Diptera: Drosophilidae) and its potential impact to wine grapes during harvest in two cool climate wine grape production regions.  Economic Entomology, 10.1093/jee/tov042.

Wiman N.G., V. M. Walton, P. W. Shearer and S. I. Rondon. 2014. Electronically monitored labial dabbing and stylet ‘probing’ behaviors of brown marmorated stink bug, Halyomorpha halys, in simulated environments. PLoS ONE 9(12): e113514  doi:10.1371/journal.pone.0113514.

 

1. What is your position at Oregon State University/OWRI?

I am an Associate professor and Horticultural Entomologist at Oregon State University in the Department of Horticulture, and a Core member of the Oregon Wine Research Institute.

2. What do you enjoy most about your work?

Working with growers, and students and being able to solve problems through discovery.

3. When you’re not working, how do you enjoy spending your time?

Spending time with my family.  We try to get out as often as possible in order to enjoy the mountains and hiking trials.  When I get the opportunity I love to do some mountain biking.

4. What inspired you to choose your career path?

I grew up in a farming family.  I’ve always had the desire to be involved in farming because of this.  Farming is of course problem solving and multidimensional.  My current job is very similar.

5. What’s the best advice you’ve ever received?

When doing any job it is about serving people, not yourself.  Excellence is important when serving.

6. Which three people (living or dead) would you invite to dinner?

Nelson Mandela, Ernest Shackleton, Erica Walton, my wife.

7. What is your vision for the future of your research?

To serve the industry and help them solve problems and improve their daily life.

This position is a twenty-four month full time position with the USDA-ARS with Dr. R. Paul Schreiner and Dr. Jungmin Lee. 75% of this position will be located in Corvallis, Oregon and 25% of this position will be located in Parma, Idaho. For full consideration of this position, a Ph.D. at the time of hire in a discipline relevant to the position (plant science, plant physiology, biochemistry, horticulture, viticulture, etc.) will be necessary, as well as verifiable expertise in research related to plant production, plant interaction with the environment, and plant metabolism.

To view the full position description, click here.

Information about Dr. R. Paul Schreiner’s program is at:
http://www.ars.usda.gov/pwa/hcrl/schreiner

Information about Dr. Jungmin Lee’s program is at:
http://www.ars.usda.gov/pwa/hcrl/lee

Applicant screening will begin on May 11, 2015.  Interested applicants should send a detailed letter of application with the following information:
Qualifications
A statement of professional and research goals
A curriculum vitae
All college transcripts
A Ph.D. thesis abstract
A minimum of three references (please include the names, addresses, and contact information)

Send to: Dr. R. Paul Schreiner (Paul.Schreiner@ars.usda.gov)

Oregon State University, in conjunction with the Oregon Wine Research Institute is currently recruiting for an assistant professor position in viticulture research and Extension. This position will be be located at the Southern Oregon Research and Extension Center branch research station in Central Point, Oregon. With the rapidly developing industry southern Oregon, there is a significant need for research and Extension. This position is also a vital part of the Oregon Wine Research Institute team, ensuring that we are offering the best in applied viticulture and outreach to the premium winegrape industry in the state of Oregon.

Details of the position are provided here, or the Oregon State University Employment website http://oregonstate.edu/jobs/. Please share with those you think may be well suited to this type of position in applied research and Extension. For full consideration, the application deadline is June 20.