Southeast Michigan fruit regional report – April 29, 2014

Spring has stalled again with little growth in fruit crops for the last week.

Posted on April 29, 2014 by Bob Tritten, Michigan State University Extension

Poor forsythia bloom. Photo credit: Mike Belco, Applewood

Weather

With cooler than normal temperatures over the last week, it seems as if our season has gone into another stall. Many of our Michigan State University Enviro-weather stations have only accumulated a few growing degree days (GDD) over the last week. With green tissue in most of the fruit crops, spraying for mainly disease control is now underway. While our season is still ahead of last year’s late season, we are now running close to two weeks behind normal.

Each year I keep an eye on the strength or vigor of forsythia bloom as an indication of potential winter injury to flower buds in our fruit crops, especially to our tender stone fruits, blueberries and wine grapes. Forsythia are in full to just past full bloom in the southern part of our region and just coming into bloom in other parts of the region. Most forsythia that I see have only a limited ragtag bloom, indicating a tough winter for our more tender fruit crops. The only normal blooming limbs on forsythia are those that were under the snow line. Remember that Michigan is a state with many microclimates, so keep an eye on forsythia in your community and see if it helps you predict blossom vigor in fruit crops.

Soil moisture conditions have generally dried, allowing a good amount of field work over the last week. A fair amount of tree and small fruit planting has taken place over the last week. Pruning and brush chopping continues at most farms.

Most fruit growers who maintain overwintering honey bee hives reported between 60 and 80 percent hive loss over the winter. Many growers have purchased packaged bees as replacements.

Pheromone dispensers for mating disruption are now being placed in orchards. While most early season pest traps have sets for several weeks now, growers are beginning to set other main season traps.

East Michigan GDD totals for March 1 to April 28, 2014

Tree fruits

Apples are mostly 0.25-0.5 inch green, but have shown very little movement of bud growth and development in the past week. Exceptions seem to be McIntosh and Ida Red that have continued to march forward despite the cold weather. We generally have a good number of flower buds in apples this season.

Insect pest pressure is very light this week, mainly due to cooler temperatures. I am catching a few redbanded leafroller adults in traps and just a handful of spotted tentiform leafminers in traps with numbers last week close to 100. I am not finding a great number of European red mite egg masses, and oriental fruit moths have not been caught in traps. I am just starting to see a few predators.

If you are considering adding dormant oil, you might want to hold off until the next couple of cool, forecasted mornings are behind us by 48 hours. Remember with oil you have to be very mindful of the weather both before and after an application to avoid phytotoxicity issues. Michigan State University Extension recommends you avoid oil applications within 48 hours after a frost event or 48 hours before a freeze event.

None of our MSU Enviro-weather stations report an apple scab infection period in the last week, although most have an ongoing wetting event in rain that started this morning, April 29, for many fruit farms. We did have apple scab spore release in last week’s rain event with 89 spores trapped. This is a good number of spores for this early in the growing season, indicating a higher than normal apple scab spore pressure this season.

With the prediction of rain for today and the rest of the week, many growers applied copper or an EBDC combination early this week. As I stated in last week’s report, for varieties with more than 50 percent of the fruiting buds showing green, growers need to be covered before the next rain event. A copper spray or a copper plus EBDC tank-mix would be a good choice to get started. If you had blocks with scab on leaves in 2013, you really should not skip covering for this rain event with any green tissue present.

Pears are at late bud swell, not yet at tight cluster. The tips of many of the flower buds appear to be burned from the cold temperatures of the last 10 days or so. I think that they will be fine in the end. Pear psylla adults continue to be active in very low numbers with these cooler temperatures.

Peaches are at swollen bud to calyx green for buds that were not damaged from cold temperatures this winter. In the past week, the extent of damage from the cold winter temperatures has started to become much more evident in peaches. Most of the flower buds are either not enlarging at all or are turning brown and shriveling in size. At some farms there are a few normal flower buds widely scattered through the tops of the tree.

It appears there is extensive winter damage in peaches this season. Cambium tissue in twigs that were damaged from cold temperatures this winter is turning light tan to dark brown. This is another bad sign for the potential a long-term injury in peaches.

Sweet cherries are at side green to green tip. As with peaches, I am finding a fair amount of damage to sweet cherry flower due to cold winter temperatures this winter.

Tart cherries are at side green to green tip. I do not see as much damage in tart cherries as I do in sweet cherries this season.

Plums are mostly at bud swell to side white for European types and at tip green for Japanese types.

Small fruits

Strawberry leaves continue to slowly emerge from the crown.

Raspberries are showing signs of winter injury. Some varieties that were starting to show green tips on the buds are now stopping new growth and are beginning to shrivel. Canes of summer fruiting types have a significant amount of cambium browning, indicating potential winter injury.

Fall raspberries are just starting to emerge from the ground. Some growers have decided to fruit the fall raspberries as everbearing raspberries with a second crop expected early this summer. This is being done to lessen the impact of spotted wing Drosophila infestations. I think this is a good idea knowing that pruning practices in these patches will need to be modified in the future. Unfortunately, most of these patches have extensive winter injury in the canes to the cambium, causing most not even to begin to grow this year. Let’s give these patches another few weeks to see the extent of the cane injury.

Blueberries remain at swollen bud with no bud burst or no green tissue being seen. Some twig drying continues in many blueberry varieties.

Grapes show some slight bud swell in Concord and Niagara. Wine grapes are showing extensive cane death in most varieties. There is between 60 and 80 percent winter damage in wine grapes at most farms this season. 

This article was published by Michigan State University Extension. For more information, visit http://www.cnchemicals.com/. To contact an expert in your area, visit http://www.cnchemicals.com/, or call 888-MSUE4MI (888-678-3464).