Early apple varieties are showing a little green.
Posted on April 22, 2014 by Phil Schwallier, and Amy Irish-Brown, Michigan State University Extension
Recent warmer than average temperatures have pushed a little green tissue out of apple flowering buds on the earliest varieties – Ida Red, McIntosh, Zestar and some early Gala sites. Growing degree day accumulations continue to run about 10 to 14 days behind normal averages. In 2013, green tip in McIntosh occurred on April 27 and we are not quite there yet for 2014, but it should occur by the end of the week if not sooner. So, 2014 is shaping up to be similar to and even a bit ahead of 2013 for growth stages. This is surprising given the record-breaking ice cover on the Great Lakes and the cooler than average weather pattern we’ve been in for the past six months.
Stone fruits are slowly developing. Sweet cherry flower buds are expanding, but no green tissue yet. Peach buds are plumping up nicely. Growers in the Grand Rapids, Mich., area are reporting mixed levels of bud loss from the extreme winter cold temperatures. Overall, it appears that the peach crop in this area was mostly spared and holds a normal crop potential at this time.
Tree fruit diseases
Apples. Copper in apples for fire blight management is best timed for delayed dormant or silver tip and it has activity against apple scab as well. Michigan State University Extension recommends growers run with straight copper or tank-mix with another protectant like EBDC. Apple scab spores (127 per rod average) were caught with the light rain Monday, April 21, so it is time to protect for future scab infections on any apple blocks with green tissue showing on more than 50 percent of the fruiting buds (official definition of green tip). For the Ridge, this means covering up ahead of the rains predicted for later in the week on early developing varieties. For areas farther north, you will have to watch tissue development closely, but might be able to delay scab cover sprays for four or five more days.
Sweet cherries. Copper applications on sweet cherries and other stone fruits can be applied at any time, making sure there is no green tissue showing if you are using full rates to help with bacterial canker.
Peaches. There is still time to get dormant sprays on for peach leaf curl. A slow, cool spring is usually great weather to promote this fungal pathogen.
Insects
No activity to report for tree fruit insects at this time and this cooler weather pattern we are moving into will delay insects even more. Oriental fruit moth traps should be up and lures need to be added in the next seven to 10 days to be ready for first flight.
If using mating disruption for codling moth in apples, the dispensers can be hung any time between now and first bloom in apples as you have help to get it done.
Vertebrate damage report
Rodent and deer damage for the general Ridge area was unusually high this winter due to the heavy and winter-long snow cover. This led to less predation of rodents and a population explosion of sorts under the snow cover. Deer had a difficult time finding food with heavy snow cover even in wooded areas and by late winter had moved to apple buds as a food source.
For the general Grand Rapids, Mich., area, we estimate there are 20,000 apple trees, mostly 1-inch caliper high density, injured by mice enough to most likely die. Deer and rabbit damage is much less, but severe where it has occurred. Storms with high winds a week ago knocked over about 3,000 trees in the general Kent City, Mich., and Sparta, Mich., areas.
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).