I recently received an email from someone newly transplanted to North Plains from Washington. In her email she said, "I found your email on a link when i googled white flies, oregon state agriculture. I want to know how to rid of these? is there a chemical i can spray on my bushes and trees?". She ended by saying, ". . . this is something i have not seen before. We have MILLIONS flying around." Below find my response to her followed by some additional comments. Robin
"You are likely seeing a recently introduced whitefly called ash whitefly. It is a huge nuisance, particularly this time of year when they are swarming around seeking overwintering sites. The good news is that Oregon Department of Agriculture personnel have found very effective natural enemies of this whitefly species in the metro area. We expect the numbers of these natural enemies to increase and eventually reduce the overall population of these whitefly below noticeable levels. Now that may take a year or two. In the meantime we don’t suggest pesticide applications in home landscapes as the whiteflies you are seeing now are not damaging most plants, new whiteflies would likely re-invade a sprayed area quickly from unsprayed surrounding areas, and we want to conserve those newly found natural enemies.
I had the benefit of witnessing the success of these particular natural enemies to control ash whitefly when it first established in California. Within the span of two years after the release of the parasites and predators, it was extremely difficult to find any signs of ash whitefly. Although annoying now and even likely to become more obvious until our first freeze of the year, we expect the populations of ash whitefly to diminish gradually over time. Patience now should be rewarded down the road.
I have more information, including a link to the find of the natural enemies by the ODA, at my website (link below). I hope this information is useful."
Added comments: While the overwintering adult stage may not directly damage a plant, it might be a plant shipment contaminant pest and intervention may be required if plant shipments occur while the whitefly is present. I have since learned from Chris Hedstrom at the ODA that he made some releases of the Encarsia inaron wasps in various locations in the North Willamette Valley in August and there was evidence of existing E. inaron wasps in all of those sites prior to those releases. In casual observations, the ash whitefly populations seem to be less abundant in areas of noticeable prior infestations but we may see those numbers increase with additional warm weather forecast for September. My caution is for nurseries to be vigilant if shipping but if not, it might be best to let the natural enemy populations build and expand.
Rufus at the WxCafé ® brings Classic Fall weather. I'll be in travel mode and gone this Friday and all of next week in order to attend the International Congress of Entomology. A reminder that you can find the WeatherCafé ® info on Mondays and Fridays at the link. Robin
Monday September 19
A classic fall weather week ahead. Hot morning beverage time.
We will experience showers today into early Tue, yielding to "turn on the heater" overnight lows, foggy bottom mornings and mild, sunny afternoons. The broad, upper level trough settling over the PNW will spread its influence deep into CA and east. Some mid-level moisture from Pacific hurricane PAINE will train NE, combine with the leading edge of the cool trough over the PNW, to set off lots of precip over ID, MT, WY beginning Thu. This will bring stormy conditions to the Rocky Mountains. The Fall Equinox is Thu the 22nd.
A wet system moves into the PNW on Fri Sep 23, with a good news ending: it should dry by sat afternoon, opening the door for a decent weekend (recall that expectations were not as bright a few days ago). Warm September temps on the way for Tue, Wed Sep 27,28. By the 29th, models bring another round of cooler air over the PNW, so expect showers to increase by late Thu, with a damp Fri to follow. Similar to the coming weekend, this damp event may spin out of the PNW by mid-day Saturday, so the first weekend of October could dry out, yet remain on the cool side. Fall.
The first week of October is progged to turn rather STORMY as a deepening center low storm rolls up the coast of Oregon on Tue morning Oct 4. Early yet, but these systems tend to be wind producers, so hoop/tunnel folks need to remain alert for the button-down call. The WxCafe (TM) will monitor closely to put out the alert should winds expect to top out above 35 mph. Again, too early to react just yet, this is merely a morn'n beverage ponder point for now. The Oct 5-7 period is trending damp.
"I smile because I don't have the slightest idea what's going on."
Is that a quote from a highly trained economist or a weather forecaster?
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Hi Everyone! There is an upcoming online class on Biological Control for Greenhouse Growers that I thought might be of interest to subscribers. It is offered by Michigan State University Extension and Kansas State University Extension and offered through eXtension, the national Extension website. Registration is currently open for this self-paced, non-credit course. For details about the class, check the link. Robin
Rufus at the WxCafé ® dampens our weekends. Will I finally be driven indoors to process all of those tomatoes from the garden? Robin
Friday September 16
Tag line got your attention? Grab that morning beverage and let's see what's up.
Back in August, we pondered what impact the seemingly early pooling of cold air over the Chukchi Sea would have on our weather here in the Great PNW. It is one of the points of interest around the ole' WxCafe (TM). The weekends ahead are going to be impacted by precipitation which is tied to the battle between cold & warm air masses. The resultant 'Zone of Confrontation' - where troughs meet ridges - is the imagery we use to help visualize what generates weather patterns at the surface. Classic examples are on the way.
This weekend: a cold front moving into western WA will bring cooler temps & notable precip into the Puget Sound overnight tonight, then spread south into western Oregon Saturday. Not a strong front, yet enough to get noticed. Moisture should also make it over the Cascades, so don't be surprised if you get a dust buster in the Columbia Basin, Spokane. Patrons in Oregon south of Eugene will likely remain dry, cooler. Short break between fronts on Sunday, then another, weaker system moves onshore late Sunday into Monday. Not as much moisture trained into this disturbance, so expect fewer showers then the preceding front as the main impact will be cloudiness and fall-like September temperatures. The cooler air will reach all the way down into northern CA. Westerly breezes throughout.
Next week, the PNW will remain on the cool side, with an upper level low overhead. Dry after Tue morning, although some moisture may 'wrap around' a surface low over MT, WY for a shower or two in the eastern portions of WA, OR Thu/Fri. By late Fri, another damp weekend unfolds.
Weekend of Sep 24,25: cold air pooling over the Gulf of Alaska will continue to generate weather along the confrontation zone noted earlier. Expect a damp Fri night & Saturday. Not heavy rain, just enough to keep umbrellas in action, esp north of Salem. Model solutions start to vary notably for Sunday. The trend is for a ridge of high pressure to rebuild, drying out the region and edging the rainy systems into northern Vancouver Is, Haida Gwaii Islands. For now, we'll write in the chance for showers returning late Sunday over the Puget Sound region on into early Monday.
Rufus at the WxCafe puts a damper on our weekends. Will I finally be driven indoors to process all of those tomatoes from the garden? Robin
A ridge will build into the Gulf of Alaska, blocking systems for a few days. This will yield pleasant, early fall weather for the week of Sep 26 - 30. Indeed, by Thu the 29th, on offshore flow will develop popping temps into the Summer of September range again, esp for OR patrons.
Weekend of Oct 1,2: here we go again. Maybe. The latest solutions indicate a cool air flow from the N-NW will push a cold front over the PNW into the region to start October with a drip. This is a ways out, so the ridge may hold. However, we always discuss the probably around here, so there is a good chance for 3 consecutive DAMP weekends. Murphy's Fall.
Given the breaks between systems, the overall wx pattern ahead will be rather favorable for grape & hazelnut harvests. Not a muddy mess, but enough precip to help dust management and remind all of us that it is September in the PNW.
"The wheels of progress are not turned by cranks."
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Rufus at the WxCafe sent this out last evening. Robin