MSU Extension

Weather

Our season jumped back to a normal timing in the last week as a result of the warm temperatures in the past week, back to normal in terms of growth stages and nearly normal if you compare growing degree day (GDD) totals to the 30-year averages. Insect activity has also begun to pick up in the last few days as a result of these above normal temperatures.

Soils have become very dry over the last week. It is amazing to see how quickly our soils have moved from overly wet to extremely dry at most farms. Many growers are getting irrigation systems up and running on newly planted tree and small fruits because soils have dried so much in the past two weeks.

Fruit drop is becoming more apparent from the freezing temperatures some growers experienced on the morning of Monday, May 13. There are widely varying degrees of crop loss on fruit farms along the US-23 corridor from the Flint, Mich., area south toward the Ohio border. Low temperatures were generally in the range of 27 to 30 degrees Fahrenheit at most fruit farms, which was just at the edge of the point where flower buds would be injured and lost. However, there were many reports from fruit growers in this affected area of temperatures being as low as 22 F in low areas or frost pockets.

With warmer temperatures and much lingering bloom, apple and pear growers have covered several times for fire blight control.

East Michigan growing degree day totals for March 1 to May 20

Tree fruits

Apples are mostly at early petal fall, with most fruitlets being 4 to 6 millimeters in diameter. Apple bloom was much longer this year than most years and some apple blocks saw a delayed bloom mostly on 1-year-old wood.

Flower bud damage was severe in blocks at lower elevations at some farms from the May 13 freeze event, with as much as 50 to 60 percent bud kill in many of these orchards. These blocks can still have a decent crop of apples this season if we don’t get more cold weather. Again, freeze damage is extremely variable across east Michigan.

Insect activity has picked up a great deal in the heat of the past week. I caught my first codling moth in traps late last week and a few growers biofixed yesterday (May 20). I am not ready to set a regional biofix date for codling moth, but expect to do so in the next few days as we continue to see more trap catches. As of today, May 21, I had my first report of San Jose scale adult male trap catch. It is too early to begin to see crawler activity. A few mullen bugs are being found in apples.

Oriental fruit moth trap catch continued last week, and I set a regional biofix date of May 16. Recall that I disregarded the May 9 regional biofix date for oriental fruit moth as a result of the cold temperatures on May 13. In other words, I started the trap catch clock over again.

I continue to see a few white apple leafhopper nymphs, green apple aphids, apple grain aphids and rosy apple aphids; however, the abundance of predators this season is doing a good job of keeping them in check. A bit of European red mite egg hatch continues; here again predators are doing a great job controlling them. Spotted tentiform leafminer trap catch continues to decline for the first generation adult flight, with a few eggs found. There are record setting numbers of predators being seen this season. This is a reflection that most apple blocks did not receive many insecticides last season due to the lack of a crop. Many growers are delaying their petal fall spray to later in the week as we have several days of rain predicted over the next few days.

I saw my first apple scab lesions two weeks ago and have not seen any since. I continue to get apple scab spore catch in my traps in the typical numbers for this time of the season. According to the spore release model on Enviro-weather, about three-fourths of the spores have been released for the season. I am seeing more twig infections of powdery mildew in the last few days, mainly on susceptible varieties. My concern continues that apple growers may be forgetting about controlling powdery mildew this season. With recent warmer than normal temperatures, some dew in the mornings and abundance of powdery mildew last season, growers need to apply mildewcides to control it.

Concern for fire blight blossom infection has been high the last few days, with EIP numbers at record levels. Many growers have covered two to three times for fire blight protection in the last eight to nine days. Keep an eye on the two models on Enviro-weather to monitor possible blossom blight situations. Remember that the predictive model allows you to put in your own data or to create mock scenarios to help you decide how to manage fire blight during bloom.

Pears are 5 to 8 millimeters for growers that have a crop this year. There has been a small amount of late bloom in blocks that lost fruit due to cold temperatures on May 13. Some of these blocks will have no fruit this season. Pear psylla adults continue to fly and egg hatch continues as well.

Peaches are at shuck split to 6 millimeters in size. Damage to peaches from the May 13 frost event is more evident this week, with some blocks only having 10 to 20 percent of a crop remaining. I saw my first peach leaf curl infected leaves yesterday afternoon. I continue to see very low to no oriental fruit moth trap catch in peaches this season, only in apples.

Sweet cherries are 6 to 10 millimeters in size with very heavy fruit drop in blocks hit hard by the May 13 freeze event. No plum curculio have been seen.

Tart cherries are at shuck split to 6 millimeters in size. As is the case with sweet cherries, there is heavy fruit drop in a few blocks. Freeze damage to tarts was also variable, with less damage than in sweet cherry blocks.

Plums are shuck split in the few blocks with a crop. Growers need to be on top of black knot sprays.

Small fruits

Strawberries are at 50 to 80 percent bloom at most farms. I continue to look at strawberry fields that do not seem to have adequate leaf growth this season. Leaf growth and flower bud development are a bit out of sync this year with this lack of leaf development. Light amounts of nitrogen will help to increase foliage growth. A water soluble application through the irrigation system will work just fine for this nitrogen application. I have not seen any strawberry clippers in the last week, but growers need to keep an eye out for them as well as tarnished plant bugs. Fungicide applications for gray mold control are being made as bloom continues.

Raspberries are at 4 to 6 inches of new growth for summer-bearing types with flowers emerging from the bud. Newly emerging canes for next year’s crop are 3 to 4 inches in length. Canes of fall-bearing types are about 12 to 14 inches tall where they were not killed back to the ground from the May 13 freeze event. New canes are emerging from the soil in these freeze-damaged plantings.

Blueberries are at full bloom for early flowering types and first bloom for most other varieties. It appears that there was little freeze damage from the May 13 freeze event, thus at this time we are set for an excellent blueberry crop this season.

Grape growth exploded in this last week with new canes at 8 inches of new growth and flower clusters now being seen. In plantings that had freeze damage from the May 13 freeze event, new growth is slow to come along. Buds that were just in the process of opening seem to be in much better shape.

Meeting announcement

Two apple thinning meetings are available this coming Thursday, May 23. The first meeting will be held at Applewood Orchards, 2988 Rodesiler Hwy., Deerfield, MI 49238 (view map and directions) starting at 11 a.m. The second meeting will be held at Spicer Orchards, 10411 Clyde Rd., Fenton, MI 48430 (view map and directions), starting at 1:30 p.m.