Yesterday we received several rains totaling 3.6 inches at a mean temperature of 70°. This volume of rain would remove most of any protective fungicide residue applied before the rains, indicating need for tightening spray intervals for summer disease control on apples and for reliable control of brown rot on peaches and other stone fruits. Scab symptoms are very evident on non-protected peaches.
Wetting hours accumulated last week (38) brought our total to 383 hours. This is less than for this time last year, but ahead of 2010 and 2011.
Tuesday, July 23, 2013
Tuesday, July 16, 2013
Disease update
Three extended wetting periods of 10-11 hours occurred July 11-14 last week; total volume of rainfall for the week was 1.06 in. These wetting periods averaged in the upper 60s and lower 70s and were favorable for summer disease development.
As of yesterday morning, July 15, at our AREC we had accumulated 345 wetting hours, well beyond the 250-hr threshold. Last week sooty blotch/flyspeck symptoms were readily apparent on non-protected trees in our fungicide test blocks. By now it might be showing up in poorly protected commercial blocks as well.
I have been away for two periods of more than a week twice in the past month, and being away for a week seems to suddenly bring out some readily visible changes that appeared while I was away. Three weeks ago I noticed that more fireblight had shown up. A lot of this was advancement of symptoms from blossom blight on late, unprotected bloom; others appeared to be from shoot tip infection (shoot blight) related to secondary infection during storms.
Another change three weeks ago, but even more obvious this week, is the intensifying orange glow from cedar-apple rust on unprotected backyard York Imperial apple trees. York is very susceptible to cedar-apple rust, and even moderate amounts of infection can significantly reduce return bloom and yield the following year. It will be interesting to see how much bloom is present on these heavily infected trees next year. Two or three sprays of the readily available Immunox fungicide from mid-April to mid-May would have prevented most of this problem.
At risk of jinxing what appears to be a good corn crop coming on, I will say that it is always a good indicator of what the weather was like in the past couple weeks. Three weeks ago I was sure it had grown 2 feet in a week; now this week it is tall and all in tassel.
By the way, our hike in Glacier Park turned up more hawthorn rust than grizzlies!
As of yesterday morning, July 15, at our AREC we had accumulated 345 wetting hours, well beyond the 250-hr threshold. Last week sooty blotch/flyspeck symptoms were readily apparent on non-protected trees in our fungicide test blocks. By now it might be showing up in poorly protected commercial blocks as well.
I have been away for two periods of more than a week twice in the past month, and being away for a week seems to suddenly bring out some readily visible changes that appeared while I was away. Three weeks ago I noticed that more fireblight had shown up. A lot of this was advancement of symptoms from blossom blight on late, unprotected bloom; others appeared to be from shoot tip infection (shoot blight) related to secondary infection during storms.
Another change three weeks ago, but even more obvious this week, is the intensifying orange glow from cedar-apple rust on unprotected backyard York Imperial apple trees. York is very susceptible to cedar-apple rust, and even moderate amounts of infection can significantly reduce return bloom and yield the following year. It will be interesting to see how much bloom is present on these heavily infected trees next year. Two or three sprays of the readily available Immunox fungicide from mid-April to mid-May would have prevented most of this problem.
At risk of jinxing what appears to be a good corn crop coming on, I will say that it is always a good indicator of what the weather was like in the past couple weeks. Three weeks ago I was sure it had grown 2 feet in a week; now this week it is tall and all in tassel.
By the way, our hike in Glacier Park turned up more hawthorn rust than grizzlies!
Tuesday, July 9, 2013
Sooty blotch and flyspeck on non-protected fruit; rot weather
As of yesterday morning, July 8, we had accumulated 293 wetting hours and sooty blotch/flyspeck symptoms were readily apparent on non-protected trees in our fungicide test blocks.
Extended wetting periods last week occurred July 1-2 (8 hr with 0.03 in. of rain at 71°) and July 7-8 (18 hr with 0.97 in. of rain at 70°). These wetting periods were favorable for rots.
Extended wetting periods last week occurred July 1-2 (8 hr with 0.03 in. of rain at 71°) and July 7-8 (18 hr with 0.97 in. of rain at 70°). These wetting periods were favorable for rots.
Monday, July 1, 2013
Last week's extended wetting and accumulated wetting hours
Last week was relatively dry, but with a 13-hr wetting period of June 29-30 with 0.14 in. of rain at 67°.
As of this morning, July 1, we had accumulated 251 wetting hours- just exceeding the 250-hour threshold for specific treatment against the sooty blotch and flyspeck fungal complex. For purposes of predicting development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. At 250 hours the organisms causing sooty blotch and fly speck symptoms are expected to be present on non-treated fruits, and symptoms will appear after a brief incubation period. Typically, symptoms will appear earlier in orchards at lower elevations where more wetting hours accumulate.
As of this morning, July 1, we had accumulated 251 wetting hours- just exceeding the 250-hour threshold for specific treatment against the sooty blotch and flyspeck fungal complex. For purposes of predicting development of the sooty blotch and flyspeck (SBFS) fungal complex, we record accumulated wetting hours from rainfall or dew, starting 10 days after petal fall. At 250 hours the organisms causing sooty blotch and fly speck symptoms are expected to be present on non-treated fruits, and symptoms will appear after a brief incubation period. Typically, symptoms will appear earlier in orchards at lower elevations where more wetting hours accumulate.
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