2015 Fruit Pest Update

April 1, 2015

read only about CHERRY

WINTER INJURY?

A new growing season for cherry and apple will soon be under way. A concern of tree fruit growers at this time is possible winter injury that may have occurred since last fall. With temperatures this past winter of -20°F or lower we expect to see some damage to flower buds. We have looked at a number of samples of both tart and sweet cherry from trees here on the station and elsewhere on the peninsula. For both species we have seen moderate to severe damage. Of the two, tart cherries have fared better with loss of viable flowers in the 50% range. On the other hand, sweet cherries have suffered much higher levels of damage and will likely not produce a crop in many plantings. Average flower loss has been in the mid to upper 90% range for most varieties. Only a few samples fared slightly better with losses in the mid 70% to 80% range of flower damage. This does not look good for a sweet cherry crop in 2015 as we still have spring frosts to possibly contend with.

As we go through the next month or so remember that critical temperatures for flower bud damage change dramatically between dormant buds and flowering. Whereas it may need to reach -20°F to -25°F to damage dormant cherry or apple buds in mid winter, cherry or apple flower buds may sustain 90% damage at 2°F to 5°F at the green tip stage of bud development.  Later, during bloom, this increase in development results in a change of temperature for 90% bud kill to only 25°F for apples and tart cherry. Remember our median last freeze date is around May 15th.

Finally, below is a degree day comparison for the last three years. We are very close to average for this time of year, only slightly ahead of the last two years , but no where near the point we were at in 2012 when degree days totals were almost a month ahead of average.

Degree day comparison 2013-2015
Date 3/25 2013 2014 2015
DD Base 32 74 49 132
DD Base 50 0 1.5 11

Links to individual Enviro-Weather stations:

Casco   Southern Door   Sturgeon Bay   Egg Harbor   W Jacksonport   Sister Bay

 

CHERRY – currently ‘dormant’ stage at the Peninsular Station

Disease Pressure Little to worry about because of plant stage

Insect Pressure Check back for reports as the season progresses

 

APPLE – currently ‘dormant’ stage at the Peninsular Station

Disease Pressure Little to worry about because of plant stage

Insect Pressure Check back for reports as the season progresses

 

GRAPE - currently ‘dormant’ stage at the Peninsular Station

Disease Pressure Little to worry about because of plant stage

Insect Pressure Check back for reports as the season progresses