West Michigan tree fruit regional report – April 12, 2016
Tree fruit development is slightly delayed, but growers should ready.
What crazy Michigan weather we’ve had for the last six months. In the Grand Rapids, Michigan, area, more snow fell in April 2016 than November and December 2015 combined. Fast forward to March and degree days started accumulating faster than even 2012 and made us all nervous. Mother Nature is tricky and cooled it down in mid-March and April. April 2016 has been nearly 10 degrees Fahrenheit cooler than normal.
Degree day totals for the general west Michigan area continue to be ahead of the normal average. We have fallen back from being 14 days ahead for base 42 to now only seven days ahead and this will continue to go backwards until this colder than normal weather moves out later in the week. The temperatures were a little warmer on Sunday, April 10, and I could see some movement in apple buds from Saturday to Monday. I am calling the official green tip for McIntosh on the Ridge for April 10, 2016. I know some sites had more green showing prior to this date, but we always use McIntosh as our indicator variety.
It’s likely that full bloom for apples will be a normal average date around May 10, give or take a week. Michigan State University Extension advises growers make contact with their bee company to be prepared.
The very cool weather halted growth over the last 10 days. That will change later this week as much more seasonable weather moves in and growth will slowly begin. I don’t expect an explosion of growth, but rather a nice, slow progression. There is not much chance for precipitation in the forecast, but be ready to put cover sprays on for apple scab for the next rain event.
Regarding apple scab, I’ve had spore rods out since March 12, 2016. Given the up and down temperature and moisture levels we’ve experienced over the winter months, I am not surprised I caught single digit spore numbers with the March 13 rain and some of the more significant rains since. Even though spores are discharging ahead of green tissue, the overall numbers are very small – only a total of 32 spores caught since March 13. You will notice on MSU Enviro-weather some of the rain events have no hours for infection listed due to the hourly temperatures being below 32 F – no spores were caught in those rain/snow events.
The most recent wetting event was just shy of the hours needed for a scab infection – at such cold temperatures, we would have needed nearly 40 hours of wetting. Spore numbers were light. A few orchards in more southern areas of the Ridge have the first fungicides sprays on already, but the majority of acres have not covered yet.
In sweet cherries, there is still time to apply dormant copper sprays for bacterial canker management, although some research suggests copper does no good due to widespread resistance of Pseudomonas bacteria to copper. If you have pruning to do in sweet cherries, this would be a good week to work on that – warm temperatures and no rain are not favorable for canker. As green tissue develops, it becomes susceptible to canker infections if something happens to allow bacteria entry into tissue – this includes frost or freezes and pruning. Avoid pruning sweet cherry in cool, wet conditions.
In peaches, peach leaf curl sprays should definitely be considered this spring if you did not get applications on last fall. The recent pattern of cool and wet weather are perfect environmental conditions for the peach leaf curl fungus to get a foothold in early developing buds.
There is no activity to report for tree fruit insects at this time. Green fruitworm could start flying soon. If you have the time, scouting for European red mite overwintering eggs should be done. Dormant oil sprays are your first defense against San Jose scale, which was significantly higher in some blocks in recent years.
The annual Spring Spray Meeting will be Thursday, April 21, 2016, from 4-6 p.m. at the Goodfellow Farm as in recent years. The address is 2267 12 Mile Rd, Sparta, MI 49345. Please use the orchard entrance near Laubach Road, west of the house drive. We will meet in the large, white building located behind the houses. This meeting is sponsored by the Michigan State Horticultural Society and MSU Extension. MDARD pesticide recertification credits and CCA credits have been granted.