East Michigan fruit update – May 12, 2020

Cold temperatures on Friday night and Saturday morning caused more damage to flower buds on many fruit crops. This damage is in addition to damage from cold temperatures on April 22.

Weather

We have had a very cold week resulting in stalled growth on most fruit crops. The net result of cold temperatures has been just a few degree days accumulating in the last week. Our season has dropped back to being between seven and 14 days behind normal for most of our Michigan State University Enviroweather stations in east Michigan. Forsythia has been in bloom for the last five weeks, which is longer than I ever remember. It is an indication of how slow growth has been progressing this spring

All the region has experienced several mornings with freezing temperatures that have affected fruit flower buds on many crops. The coldest temperatures of the past week were this past Saturday morning, May 9. Many of our MSU Enviroweather stations recorded temperatures that dropped well below freezing much before midnight and temperatures remained below freezing to well after sunrise. I have had many reports from fruit growers with temperatures in the 25 to 27 degrees Fahrenheit range. Many strawberry growers saw temperatures at ground level being 19 F.

I am seeing a good amount of damage on flower buds in tree fruits. Overall, I see crop loss for tree fruits in the range of 40 to 60%. There wasn’t much freeze damage to small fruit crops. Recall that we also had cold temperatures on the morning of April 22 that also saw some damage to fruit crops. See each section in the report that follows for more details on freeze damage.

Even with rainfall last Saturday, soils remain dry for this time of spring.

East Michigan growing degree day totals for March 1 to May 11, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

268

186

92

Deerfield (Monroe County)

350

251

139

Emmett (St Clair County)

253

172

83

Flint (Genesee County)

318

224

112

Freeland (Saginaw County)

252

171

79

Lapeer (Lapeer County)

289

203

102

Pigeon (Huron County)

193

125

54

Romeo (Macomb County)

273

186

88

Tree fruits

Apple growth stages have been stalled in the last week. Most apples remain at full pink to a few early flowering varieties starting to see just a few king blossoms open. With warmer temperatures predicted for later in the week and weekend, I would expect to begin to see some bloom in apples on Friday or Saturday.

With cold temperatures this past Saturday morning, I am finding a good amount of damage to flower buds in apples. The range of damage varies widely across the region, but if I had to place a figure on flower bud loss, I would put it to be nearly 50%. Most varieties still have a crop, but this freeze was more than a good thinning freeze. This crop loss of many king blooms will make thinning decisions much more difficult.

I don’t have any new insect pests to report in apples this week. We are still finding high redbanded leafroller adult trap catch with some trap catch in the range of 200 to 220 adults per trap. Last week I was finding just a few very small red banded leafroller larvae, but this week they are easy to find in many apple blocks. Many farms are continuing to find high numbers of spotted tentiform leafminer adults in traps, in the range of 800 to 1,000 adults per trap. This insect has not been a problem for most apple growers for the last 20 to 30 years. A few more farms are starting to find oriental fruit moth adults in traps.

Surprisingly, even more predators are being found this week, despite very cold temperatures over the past week. Good numbers of ladybug adults and green lacewing larvae are being seen.

Most apple growers had an apple scab wetting event on Saturday, but due to very cold temperatures, none found that they had enough wetting for an infection period.

Pears are mostly at full white to a few varieties at first bloom. I have not seen any flower bud damage in pears from cold temperatures. Pear psylla adults continue to fly on warmer afternoons, but due to overall cold temperatures, I am not finding their numbers to be increasing.

Peaches have moved from full bloom last week to petal fall or post bloom this week. With cold temperatures damaging flower petals, it is hard to say their growth stage. I checked a good number of peach flower buds yesterday and many flower buds have an off-colored ovule that is light brown to lemon colored. I hope this is not a sign of flower bud damage, but this may be the case.

Sweet cherries are at full bloom to petal fall, but because of cold temperatures over the weekend, many flower petals have frost damage and have turned brown before dropping off. I am finding a good amount of freeze damage in sweet cherries from the May 9 freeze. Damage ranges from 40 to 60%. Some flower buds are still viable, but the crop potential has diminished greatly. The best description of our east Michigan sweet cherry crop at this time is that we have gone from a great crop of sweets four weeks ago to a good crop of sweet cherries three weeks ago after the April 22 freeze, to short crop this week after the May 9 freeze.

Tart cherries are at first bloom to king bloom. In cutting a good number of tart cherry flower buds yesterday, I found more damage to flower buds this week than last week. I estimate the damage to be in the range of 50 to 80%.

Plums are at full bloom for European varieties and early petal fall for Japanese varieties. There is some freeze damage in all plum varieties, around 60% in many varieties.

Small fruits

Strawberry flower buds continue to emerge from the crown, with some early varieties at first bloom on plants at the ends of rows and along field edges. While new leaves continue to emerge from the crown on fruiting plants, none of the leaves have expanded to full size, and most are not looking healthy. I hope that with warmer temperatures over the weekend that by next week at this time leaves will start to fill out nicely.

Most strawberry growers have had a very busy week of frost protection with many growers needing to protect four to six times in the past week. The freeze event of Friday night and Saturday morning was most unusual; most growers started to frost protect around 9 or 10 p.m. on Friday evening and continued to run irrigation to 9 or 10 a.m. the following morning. Thick ice formed, many seeing over an inch of ice on flowers and leaves, thicker than they can ever remember.

Last week I reported growers finding black flower blossoms from the April 22 freeze. Many growers were caught off guard that night and missed frost protecting berries. In the end, I don’t think this will impact our yield in strawberries.

I am finding a good amount of grass from mulch germinating in strawberry plants in the past week. Grass herbicides are being applied at this time to control it.

Newly planted strawberry leaves continue to slowly emerge from the crown. Growers can start to see the row developing.

Raspberry growth has stalled in the past week. Summer red raspberry leaves on fruiting canes are 1 inch in length and newly emerging canes are 3 inches in length. Canes on fall raspberries have emerged and most are 2 to 4 inches in length. These emerging leaves look tough from cold temperatures.

Blueberries are mostly at pink bud. I have seen some damage to flower buds in Jersey from the April 22 freeze, but no new freeze damage from cold temperatures on Saturday morning.

Saskatoons are at full bloom. There does not appear to be any freeze damage in saskatoons at this time.

Grapes are moving slowly this spring. Most are at swollen bud to a few at bud cracking open stage of growth stage.

Haskaps are at small fruit for most buds. They flower over a long period of time.

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