Summer disease update

Summer disease pressures remained steady last week.  The extended wetting event Aug 10-11, in progress at the time of the last post, amounted to 12 hr wet at 71° with 0.31 in. of rain.

As of the Monday morning, Aug 17, total accumulated wetting hours (ACW) at the AREC were: at 909 ft elevation, 864 hr; at 952 ft elevation, 611 hr; and at the 983 ft elevation, 539 hr ACW. Since accumulation of wetting hours began May 14, this represents an increase of 4.4 wetting hours per foot of elevation drop from 983 to 909 ft. The wetting hour accumulation differential is greater during times when wetting is from dew rather than during wetting from rain, because rain tends to wet both locations similarly. In the past 10 days we have recorded only 0.17 inch of rainfall, but recorded 87 hours of wetting from dew at the 909 ft elevation.  This is why we say to scout for sooty blotch, flyspeck, and fruit rots at lower elevations in an orchard.

At Tyro, in Nelson County, total ACW as of Monday morning, Aug 17, were: at 941 ft elevation, 718 ACW; at 1165 ft, 385 ACW; and at 1465 ft, 433 ACW. An extended wetting event with substantial rainfall was recorded at Tyro Aug 18-19, 16 hr wet and 1.2 in. of rain at 74-69°.

Increasing summer disease and brown rot pressures

Summer disease pressure increased in the past week, with two extended wetting events at our AREC: Aug 6-7, 16 hr wet at 68-65° with 0.11 in. of rain and Aug 9-10, 16 hr wet at 74-72° with 0.52 in. of rain. (Another extended wetting event is in progress at the time of this post).

As of the Monday morning, Aug 10, total accumulated wetting hours (ACW) at the AREC were: at 909 ft elevation, 796 hr; at 952 ft elevation, 567 hr; and at the 983 ft elevation, 518 hr ACW. Since accumulation of wetting hours began May 14, this represents an increase of 3.8 wetting hours per foot of elevation drop from 983 to 909 ft.

At Tyro, in Nelson County, total ACW as of Monday morning, Aug 10, were: at 941 ft elevation, 670 ACW; at 1165 ft, 368 ACW; and at 1465 ft, 409 ACW. 

The recent wetting events will again increase brown rot pressure on ripening peaches, as well as sooty blotch, flyspeck and rots on early ripening apples.

Summer disease update

Summer disease pressure was moderate in the past week, with one extended wetting event at our AREC: July 28-29, 13 hr wet at 72-66° with 0.59 in. of rain. A thunderstorm during the early morning hours Aug 4 resulted in only 0.15 inch of rainfall and 4 hr wetting at our AREC, but the rainfall was likely much heavier in some Frederick County orchards.

As of the Monday morning, Aug 3, total accumulated wetting hours (ACW) at the AREC were: at 909 ft elevation, 739 hr; at 952 ft elevation, 522 hr; and at the 983 ft elevation, 476 hr ACW. Since accumulation of wetting hours began May 14, this represents an increase of 3.6 wetting hours per foot of elevation drop from 983 to 909 ft.

At Tyro, in Nelson County, total ACW as of Monday morning, Aug 3, were: at 941 ft elevation, 643 ACW; at 1165 ft, 352 ACW; and at 1465 ft, 393 ACW.