MSU Extension

Weather

Warmer temperatures this past week have pushed ahead our fruit growth to a point where we are about four to six days behind normal when comparing our degree day totals to the 30-year average, and only about three to four days behind normal when I look at typical flowering days of our different fruit crops. This does vary from fruit crop to fruit crop, however, as strawberries are eight to ten days behind normal bloom dates.

Soils have dried at most farms to a point where both tree and small fruits have been planted in the last week. I will add, however, that there are some growers with heavier soils that have not been able to even work ground, let alone start to plant. Some heavier soils have dried so quickly that they seem to go from being too wet one day to forming a rock-hard crust the next day.

Most apple growers have been able to keep apple scab control sprays current over the past week. There have been several good windows to make applications of fungicides in less windy conditions. With warmer temperatures predicted for later in the week, apple and pear growers are concerned about possible fire blight infection conditions.

Herbicides have been slow this spring to show signs of beginning to work. I have told growers that have asked about this to wait for soils to warm a bit more, and then determine if a reapplication may be necessary.

Growers continue to work at pruning stone fruits. Pheromone disruption dispensaries have been applied at most farms.

Southeast Michigan growing degree day totals for March 1 to May 9, 2011.

Tree fruits

Apples are mostly at early pink, with Idared and other early flowering varieties at open cluster. Northern spy are notably behind at tight cluster.

I had the first report of oriental fruit moth trap catch on Monday (May 9), and one apple block that biofixed this morning with 10 adults caught in a trap. I expect to see trap catch numbers continue to rapidly increase this week with warmer temperatures. Other new pests to report this week include first sighting of fruit tree leafroller and redbanded leafroller larvae; a few rosy apple aphids curling leaves; a few apple grain aphids; and spotted tentiform leafminers laying eggs. I continue to see normal trap catch numbers of spotted tentiform leafminers (300 to 800 per trap) and redbanded leafrollers (35 to 60 per trap). I have not seen any plum curculio, woolly apple aphid or mullen bugs yet, but expect to find some later in the week. I found a few tarnished plant bugs feeding on flower clusters last week and expect that with warmer weather to find more this week. European red mite numbers remain low. I continue to find new predators in apples; this week I found a few Amblyseius fallacis and brown lacewing.

Apple scab spores continue to be caught in traps in increasing numbers with each wetting event. I expect to find lesions from earlier infection periods in the next day or so. As mentioned in the weather section of this report, with bloom expected later in the week, I expect that fire blight infection will become an issue if predicted higher temperatures and rain take place late this week.

Pears are at white bud. Pear psylla adults continue to fly and I continue to find egg hatch.

Peaches are at pink for Red Haven, with earlier varieties at full bloom. As mentioned in the apple section, I have had several reports of oriental fruit moth trap catch and biofix. Growers continue to prune peaches.

Sweet cherries are full bloom for early flowering types and at first bloom for later flowering varieties. We have a good number of buds on sweet cherries this year.

Tart cherries are at white bud to first bloom.

Plums are at white bud for European types and a full bloom for oriental plums.

Small fruits

Strawberry leaves continue to emerge from the crown and have grown a great deal in the past week. Strawberry rows have filled out quite nicely over the last two weeks and are looking more like normal. Flower trusses are just starting to emerge. Growers need to be ready to begin to frost protect with the first frost event of the season. Where angular leaf spot was an issue last year, growers need to consider copper applications at this time. Many strawberry fields require an extra application of a nitrogen fertilizer to help promote more vigorous leaf growth.

Raspberry leaves continue to emerge for summer bearing raspberries, and new canes continue to emerge from the ground for fall bearing raspberries. Many canes of fall bearing raspberries are now four to six inches in length. Winter damage to the tips of summer red and black raspberries is becoming more evident.

Blueberries are at early pink bud with a nice crop coming along. New mummyberry trumpets have not been seen in the last weeks.

Grapes are at late bud burst for concords and at late bud swell for French hybrid varieties; these continue to show signs of winter injury.