April 26th was my last forecast and since this time there have not been suitable weather conditions for infection.
First apothecia cups and susceptible tissue for infection were first observed in Kings County on April 17th and individual cups only remain active for two weeks. Assuming a staggered emergence of apothecia cups over a one week period, the primary infection period in Kings County should be wrapping up around May 8th. To test this projection, apothecia cups were collected the morning of May 7th (this morning) and were found to be non-sporulating and thus non-pathogenic. However, significant precipitation is forecast for Wednesday – Thursday, May 9th and 10th, so depending upon your last spray date, growers may still wish to protect for this period as a precaution against late infection risk.
For your interest, there have been four infection periods at the cooperator site in Kings County so far this year. The dates of these events and their conditions are detailed below:
• Morning of April 22nd – 7.5 hours leaf wetness and average temperature of 15.65 °C
• Evening of April 22nd through most of April 23rd – 24.25 hours leaf wetness and mean temperature of 10 °C
• Evening of April 23rd through early morning of April 24th – 12.75 hours of leaf wetness and mean temperature of 16.5 °C
• Morning of April 24th – 4.25 hours of leaf wetness and mean temperature of 17.7 °C
In summary, there has really only been a three day stretch where bushes were at risk so far this year. Do you have a history of the disease? Were your bushes protected for this period?
I remind you that this forecast is based on data collected from the cooperating site in Kings County and is a guide only for fields to the east, south, and west. The mummy berry season in southwest Nova should be slightly ahead of the Kings County site while fields to the east of the Valley should be slightly behind.
