Mummy Berry Forecast for May 7th!

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.

Mummy berry forecast for April 26th

It’s been one week since my last forecast and I can report that conditions suitable for infection have occurred at least three times during this time. The first infection period began on the morning of April 22nd and there have been at least two additional periods suitable for infection since this time. If you have a history of mummy berry disease on your farm you would have been well advised to have applied a protectant prior to this period of wet weather and should consider a second application 7-10 days later. If you did not apply a protectant prior to the current wet period, it is strongly recommended that you apply one at first opportunity to take advantage to the 72 hour “back action” capability of Funginex, Topas, or Mission so as to minimize infection. At present, all varieties are at or beyond the optimum F2 stage for infection and apothecia cups are present and sporulating under the current conditions. Protectants should be in place if you have a history of mummy berry disease on your farm!

Mummy berry forecast for April 19th!

I know it has only been two days since my last forecast but I am not going to be in my office until Monday and I wanted everyone to consider the following:

As of today, early and mid-season varieties in Kings County are at the ideal stage for mummy berry infection. There are also apothecia cups (inoculum) present and although we haven’t had suitable weather conditions for infection yet, the forecast for Sunday, Monday, and Tuesday is for warm temperatures and rain, ideal conditions for infection. I would recommend keeping an eye on the forecast for any significant change but if it doesn’t I would strongly recommend applying a control prior to this rainy period. Keep in mind that for effective “back action” you have to apply a control within 72 hours of the beginning of a wet period and if you have a long wet period, such as in the present forecast, this can be difficult.

Good luck!

Mummy berry forecast for April 17th

The following observations were made at the test site at Tim Strong’s in Kings County on the morning of April 17th:

1. Mature apothecia cups were found at the site,
2. Varieties varied from 0 to 50% F2 (susceptible) stage for mummy berry infection.

In Nova Scotia, we manage the primary phase of mummy berry disease and the conditions necessary for primary infection include 1) inoculum presence, 2) susceptible bud development stage, and 3) suitable weather conditions. At this time, in Kings County, we have met conditions one and two (for early varieties); however, we have not yet had suitable weather conditions for infection.

The decision to spray for mummy berry disease depends almost entirely on the past history of the disease in a particular field. If growers have experienced a problem in the past, they should apply controls.

A ‘fixed spray schedule’ may be used to manage the disease whereby the first fungicide spray should be applied when 40-50% of the flower buds have reached the F2 stage (flower bud scales separating). One or more additional sprays may be required on a 7-10 day schedule.

Alternatively, a ‘weather based spray schedule’ may be employed. This strategy uses temperature and leaf wetness duration to determine if an infection period has occurred. If an infection period occurs and mature apothecia are present, and flower buds are at 40-50% F2, then the grower has up to 72 hours after the start of the wet period to apply Funginex, Mission, or Topas. An additional spray(s) may be required, depending on weather conditions, 7-10 days later.

If you choose to employ the fixed spray schedule, a first spray to early flowering varieties can be applied anytime in Kings County. If you choose to wait for suitable weather conditions for infection, I will be monitoring and reporting as they occur at the station in Kings County. At this time we have not had suitable conditions for infection. Keep in mind that weather conditions can vary greatly across the Province and that bud development stages can vary considerably from location to location. The station in Kings County is a guide only for spray decisions in other areas.

1st Mummy Berry Forecast of 2012

I am delivering a mummy berry disease forecast again in 2012. Please keep in mind that Tim Strong is my co-operator on this project and recommendations will be based on weather data collected on his farm on Brooklyn Street here in Kings County. It should be fairly accurate for other growers in Kings County but will be a guide only for growers west, south, and east of his location. To review the disease, its symptoms, and life cycle, please examine the factsheet at AgraPoint’s website titled “Mummy Berry Disease in Highbush Blueberry”.

The important thing to remember about the disease is that you need three things for infection to occur – inoculum, susceptible bud development stage, and suitable weather conditions. At this time we do not have inoculum or susceptible bud development stage so there is no need to spray for the disease. However, we are getting close as early pinheads have been observed at Tim’s and with the warm temperatures this week buds are fast approaching the susceptible development stage. Growers should be prepared to spray early next week depending on weather conditions.