SW Michigan Fruit Update
May 2, 2006
Last week was cooler. Temperatures were in the 60s during the day and 30s at night. A storm system Monday and Tuesday brought light rain and cold air. There was a radiation freeze Wednesday morning (4/26/2006). Temperatures dropped into the 20s. The lows ranged from 29 to 27F at the higher less frost-prone sites to 22 to 24 in the lower frost pockets. Damage was extensive but varied from site to site due to elevation and air drainage and plant development. Growing Degree Day accumulations are a week ahead of normal for this time of year. Widespread rain fell all day Sunday bring about 0.3 inches of rain. This was an infection period for many diseases with 20 to 30 hour of wetness and an average temperature of about 55F. Soils are still dry. Soil temps are in the mid 50s. This week’s forecast is for warmer, wetter weather, with highs near 70 and lows above 50. See the new Weather for IPM decisions in Michigan site at http://www.enviroweather.msu.edu/home.asp.
Southwest Michigan Growing Degree Day Totals March 1 through April 30, 2006 |
Grapes, April 1 |
|||
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
423 |
331 |
208 |
178 |
|
436 |
334 |
202 |
170 |
|
455 |
350 |
214 |
180 |
|
398 |
301 |
181 |
154 |
|
Lawton (est.) |
460 |
357 |
232 |
217 |
South Haven NEW |
273 |
217 |
139 |
|
455 |
343 |
214 |
187 |
|
379 |
286 |
171 |
143 |
|
Lawton site is estimated using Bainbridge data for March. |
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Tree Fruit
Tree fruits were damaged by the freeze Wednesday, April 26, 2006. Bloom for most fruits were extensively damaged. Higher fruit sites generally suffered less damage. Southern sites suffered more because they were further along and because colder low temperatures were to the south. Large fruited types (i.e. apples, pears, and peaches) will suffer less loss because they need fewer fruit for a full crop compared to cherries.
Apricots in the shuck were extensively damaged. All but the best sites have little fruit left.
Peaches at petal fall. Damage was severe in some sites. Bloom was very heavy so there is still a marketable crop in many orchards. We set Biofix Oriental Fruit Moth as April 16 with a GDD of 180 Base 45 at SWMREC. Chemical controls are focused on egg hatch about 150-170 GDD base 45 after Biofix. We are about 140 GDD past Biofix and treatment should be applied soon. Sunday’s rain was a marginal brown rot infection because of the cool temperature and was also probably too cool for bacterial spot.
Sweet cherries are in the shuck and were hurt hard by the freeze. Growers with good sites report they still have a crop but lower orchards show extensive damage. Cherry leaves are unfolding so growers need to protect against cherry leaf spot. Sunday’s rain was a marginal cherry leaf spot infection in some locations.
Tart cherries: Montmorency cherries are at petal fall and were in full bloom during the freeze. The heavy bloom apparently protected most of the flowers because there was generally only light damage. Damage estimates are about 20% loss. The most common symptom was browning of the style where it joins the pistil. These flowers are unlikely to set fruit. By Monday dead pistils were easy to find and identify. Leaves have unfolded and growers need to protect against cherry leaf spot. Sunday’s rain was a marginal cherry leaf spot infection.
In Plums, Oriental plums were in the shuck and hit hard by the freeze. European plums were at full bloom and suffered less damage. Sunday’s rain was certainly a black knot infection. Plums are now at petal fall and Sunday’s rain was a marginal brown rot infection.
Apples are blooming. Many open flowers were killed by Wednesday’s frost. In many cases the king bloom and some of the side bloom are dead. Early varieties in lower sites were hardest hit. Later varieties were only lightly affected. Sunday’s rain was an apple scab infection. Symptoms should appear about May 14. Scab symptoms from earlier rains should be appearing but none were found Monday. Warm wet conditions this week means that growers need to maintain scab protection. While the weather is warming there is no danger of a fire blight infection this week, as the warm weather will not last long enough to allow bacteria populations to build. So far the dry conditions have kept fire blight cankers from doing much oozing, but I expect a lot of ooze in orchards with cankers this week. An extended warm period later in bloom could easily result in fire blight blossom infection towards the end of bloom. Growers can monitor wetting periods for scab and fire blight infections at the Weather for IPM decisions in Michigan site. We are now trapping Redbanded Leafroller and Oriental Fruit Moth. No codling moths were trapped this week. We expect the flight to begin with warm dry weather. This week will be too cool for thinning. The wet cool weather and the frost should make thinning easier. Grower should be prepared to thin apples next week.
Pears are at petal fall and were not severely affected by the frost. Growers need to protect against pear scab.
Small Fruit
Blueberries are at early pink bud and little damaged by the freeze. Early varieties beginning to bloom were hurt but generally there are still lots of good flowers left. Wet conditions during bloom mean that growers should be protecting against mummyberry and anthracnose fruit rots and botrytis blossom blight. Mummy berry mushrooms should be easier to find after the rain. Traps should be out for cranberry fruit worm.
Grapes were the hardest hit by the freeze suffering severe damage. Juice grapes were more advanced than wine grapes and have more obvious damage. Over large areas almost all the growing shoots were killed and growers report that many secondary buds had pushed and were killed also. This freeze was similar to one in April 2002 that killed most of the shoots. In 2002, several weeks passed before secondary bud growth was evident. Initial estimates of primary bud mortality are about 25% in good sites up to 100% in many areas. Secondary bud mortality is also high is many areas. The potential juice grape crop has been reduced by at least 50% and probably more. Wine grapes suffered much less damage. A more accurate estimate can be made in about a month when the flower clusters in new replacement shoots are apparent. Growers with large areas of good growth should continue their disease control programs. Growers with only scattered live shoots will want to wait until closer to bloom to decide in they should continue to protect the crop. This decision needs to be made in time to allow the prebloom spray, which is very important.
Strawberries are beginning to bloom. Growers protected against the freeze with sprinklers, but in some causes the flowers still froze. This could be due to turning on the sprinkler system too late when temperatures are already near freezing or a simple failure of the system to protect down below the low 20s. Growers should consider fungicide applications at bloom under these wet conditions.
Raspberries leaves are emerging on blackberry and summer raspberry canes. Fall raspberry shoots are 4 to 6 inches tall. The freeze did burn some new shoots on the ground and on the canes but the plants should recover with a good crop.
Cranberry buds are beginning to swell and some areas of the beds are greening up.
Miscellaneous
Growers are planting trees, and report that soils have been very dry. The recent rains are badly needed.
The next Monday Fruit Update meeting will be, Monday May 8, at the Fruit Acres Farm in Berrien County, at 5 PM.
