Northwest Michigan fruit report
Most crop growth is behind last year’s average due to late snowfall and ample moisture last week.
We have had ample moisture in the past week and last Wednesday (April 20), the region received 6-8 inches of snow. Green tissue is just starting to show in cherry and apples are only at silver tip. These differences are incredible as we were at full bloom in cherry at this time last year.
Things are moving slowly in the north. We have only accumulated 28 GDD Base 50 and 97 GDD Base 42. These accumulations are far behind a 21-year average, and these averages are 180 GDD Base 42 and 73 Base 50. High temperatures reached into the mid-60’s Monday, April 25, but most daily highs have remained in the 40’s and low 50’s.
With the slow warm up, growers are still pruning, and the snow fall presented a challenge for removing brush from the orchard. Lots of tree planting will be taking place this spring, and growers are waiting for soils to dry out.
Apples around the region are starting to move, and with rain in the forecast, the time for early season control and copper applications is now for many area growers (copper should not be applied past quarter-inch green). Although we cannot be sure that overwintering apple scab ascospores are mature and will discharge with these first rains of the season, protective copper applications are recommended, particularly in sites with high levels of infection in 2010. Early season control of primary scab is vital to mediating infection later in the season as leaf area expands. Bill Shane and George Sundin put together a great article on available copper formulations “Copper Formulations for Fruit Crops” that growers may find useful.
Things remain relatively quiet in cherry, with sweets a little ahead of tarts with some varieties at the station showing a bit of green tissue. Bacterial canker is a concern as we head into some potentially cool and rainy weather. Early copper sprays are the most common method of control for bacterial canker on cherry. Keep in mind that sweet cherry tissues are extremely sensitive to copper, and the sprays must be accurately timed to reduce P. syringae inoculum without causing phytotoxicity. If the trees are still in the dormant stage, two copper applications may be applied at 1 to 2 week intervals at a rate 1.2-2lbs of metallic copper with either one pint of spray oil per 100 gallons of water or 6-9 lbs of hydrated lime per acre. If the trees have broken dormancy and are in the pre-bloom stage (bud swell through white bud), copper rates should be reduced to 25-35 percent of the dormant rate. Up to two copper applications with a one week interval should be used at this time.
In tart cherries, copper compounds can be used at the 1.2-2lb actual copper rate at bud burst with weekly repeated applications until late May. Some of these later sprays may result in some leaf yellowing, bronzing, and potentially defoliation—adding hydrating lime at 6-9 lbs/acre will reduce the phytotoxic effects of copper. Do not apply copper at temperatures above 75°F. Again, see Bill Shane and George Sundin’s article on available copper formulations Copper Formulations for Fruit Crops.