MSU Extension

This week’s regional reports:

• Southwest Michigan - Mark Longstroth, Bill Shane, Diane Brown

Southwest Michigan – Mark Longstroth, Bill Shane, Diane Brown, Michigan State University Extension

High temperatures near 80 and lows in the 50s should continue to Friday (March 23) when we will see a good chance of showers and cooler temperatures. Next week will be a little cooler with highs in the 70s and 60s and lows above 40. This will slow down the plants a little, but not a lot. Plant development is weeks ahead of normal. Showers are forecast for Friday and growers should be prepared for warm rains at temperatures around 60.

Many fruit crops will need protection from disease, especially if bloom is present or green tissue is exposed. Weeds are also growing rapidly, and herbicide application timings needs to be adjusted accordingly. You can check for a local weather station at Enviro-weather. You can check summaries of weather or compare the current growing degree days between stations at one station for the last five years.

Tree fruit

Tree fruit are moving rapidly with the warm temperatures. Growers need to insure that newly planted trees have sufficient water from the very beginning and may need to use a nurse tank to water at the time of planting. Mark Longstroth in Van Buren County records bloom dates and has records back to 1980, thanks to Mike Thomas, his predecessor.

Stone fruit generally require a brown rot spray during bloom, maybe two if warm, wet conditions occur. Orchards with brown rot mummies from last season in the tree have more disease pressure to counteract.

Apricot bloom began on St. Patrick’s Day (March 17). The trees were quickly at full bloom. The Van Buren County average date for apricot bloom is April 18.

Peach bloom began and reached full bloom for many varieties on the first day of spring (March 21). The Van Buren County average date for peach bloom is April 27. Use of low rates of copper for bacterial spot suppression should be used cautiously. Do not reapply copper if rain has not washed off most of the previous application. Pheromone disruption for oriental fruit moth should generally be in place by petal fall in order to protect new foliage from invasion by the larvae.

Non-showy peach bloom in Berrien County.

Sweet cherry buds have burst. Early blooming cultivars are opening and we expect full bloom on March 21-22, depending on the variety. The Van Buren County average date of cherry bloom is April 25.

Tart cherries are at bud burst, moving into tight cluster. We will soon see early bloom and expect full bloom by the weekend. My average date for tart cherry bloom is May 1.

In plums, Japanese plums reached full bloom Monday (March 19) and Tuesday. The Van Buren County average date of bloom is April 21. European plums are past bud burst and into tight cluster and white bud. We expect bloom by Friday. The Van Buren County average date of bloom is April 29. Black knot requires wet conditions for infection.

Apples are at tight cluster to first pink. We will see pink in early varieties Wednesday (yesterday). Growth is so rapid that growers need short spray intervals to cover new emerging leaves. Materials that are recommended for seven- to 10-day intervals might need to be applied at three- to five-day intervals. Growth dilution of systemic fungicides will also require short spray intervals. It would be well worth watching the weather and trying to apply protectants as close to wetting periods as possible to get maximum protection from your sprays.

The MSU apple pages have an apple scab page that includes the Mills table for assessing risk from temperature and length of wetness. After and during a rain event, growers can use the apple scab infection tool on Enviro-weather to track infection periods. The use of copper fungicides can cause damage to green tissue after tight cluster. (For more on apple scab, see George Sundin’s article, “Use fungicides for apple scab protection prior to anticipated early infection periods.”

Pear buds have burst and are at tight cluster. Pear psylla are out. Growers will need to protect against pear scab.

Small fruit

Grape buds are swelling rapidly and are in various stages of development, depending on variety. Bud burst was seen in Concords in warm, sandy sites near Paw Paw, Mich., and Lawton, Mich. A number of different grape varieties were checked Wednesday at Southwest Michigan Research and Extension Center (SWMREC). The most advanced was Marquette at budburst, followed by Concord, Niagara, Marquis, Gewürztraminer, and the table grape Mars at late bud swell. Riesling was at early to late bud swell. Cab Franc and Merlot were at early bud swell and Chardonnay was at scale crack to early bud swell.

Growers making applications of copper or sulfur for early season disease control should be cautious about application to sensitive grape varieties if they have reached bud burst. Steely beetle could be found wandering about on vines where the buds were most advanced, although no feeding damage was visible.

Blueberry flower buds have burst and leaves are emerging and unfolding. Mummy berry trumpets are scarce. Most of the trumpets observed were small. Either they were just getting started or the hot, dry weather was delaying development. Mummy berry shot strike infection periods are likely during the rains forecast later this week. Growers should scout for mummies and monitor the likelihood of rain and be ready to apply controls for mummy berry.

Strawberry flower trusses are emerging from the crown. Now is a good to apply preemergent herbicides for early season weed control. In the high tunnel plantings at SWMREC (growing on black plastic, tunnel not yet covered), strawberries are in bloom.

In brambles, leaves are unfolding. In the high tunnels at SWMREC, raspberry and blackberry leaves are expanding.

Upcoming meetings

• Sweet cherry pruning demonstration for trees on Gisela rootstock on March 26 at Fruit Acres Farms.
• Thursday evening grower update meetings planned in Berrien County on March 22 at SWMREC and in Van Buren County on March 29 at the Lawrence Conference Center in Lawrence. There is a $5 charge for these evening meetings and they start at 6:30 p.m. These meetings will address current insect and disease control concerns in blueberries, tree fruits and grapes.
• Our regular Monday fruit meetings start on April 9 at Fruit Acres Farms at 5 p.m.