June 1, 1999

WEATHER:

Evaporation rates rose significantly by late last week, with 4 days at or above 0.30"/day. The total for the week was 1.76". Fortunately, much needed rain has fallen during the past 9 days. At the NWMHRS, evaporation for May totaled 5.92", which equates to a need for about 4.4" of water to meet crop needs. Rainfall during May totaled 2.65". Warm temperatures late last week provided the first good opportunity for apple thinning.

GDD 50: 417; GDD 42: 789

Apricot: Harcot – 24mm fruit
Plum: Stanley – 12mm
Apple: Red Delicious - 10mm
Sweet Cherry: Napoleon – 14mm
Tart Cherry: Montmorency – 13mm
Grapes: 16" shoots

COMMODITY REPORTS

Sweet cherries need to be protected against plum curculio. Stings have been found in commercial orchards. Bacterial canker leaf symptoms are expected to be visible late this week.

Tart cherries are currently 288 DD50 after full bloom, growers should have tart cherries protected by 375 DD50 after full bloom at the latest. In the warmer areas of NW Michigan, tarts should be protected against PC by this weekend at the latest. Green fruitworm are 3/4" long, but low in numbers this year. At the NWMHRS, we are 4 weeks after full bloom, which is an ideal time for Gibberellic acid sprays to be applied. It is important to remember that it is better to be too late than too early with these sprays. Trunk sprays for lesser peach tree borer and American plum borer should go on this week.

Apple growers should expect the results of thinning to be visually noticeable in 10 days after they were applied with average temperatures. Plum curculio stings can be found in abandoned orchards. Codling moth trap catches are on the rise. Growers in low pressure areas of NW Michigan should biofix when an average of 5 moths are caught per trap. White apple leafhopper nymphs can be found on the underside of leaves. Green apple aphids are building their colonies, but few of them at this point. European red mites continue to be scarce. Dogwood borer larva can be found in burrknots on apple rootstocks.

Peaches and apricots can both be injured by tarnished plant bugs and other plant bugs. Growers should have on an insecticide before mowing their orchards. Mowing can drive the tarnished plant bugs into the trees from the orchard floor.

Plums should be scouted for European red mites and plum curculio.

MISCELLANEOUS

Sovran just received a new registration for use on apples. It is not labeled for use on cherries, but want to add a note of warning that it has shown severe phytotoxicity on a few varieties of sweet cherries, including Sweetheart, Van and some other varieties or selections with Van parentage. Therefore, do not allow to drift on these cultivars and clean sprayer between application to apples and using the sprayer on sweet cherries with sensitive varieties. Most important Michigan varieties have shown no phytotoxicity when treated in research trials.

We heard this morning, during the Fruit Crop Advisory Team conference call, that Sovran has just received registration for use on apples. It has shown good promise for use in blocks where scab symptoms have developed. We'll send out complete information in next week's FruitNet. If you have questions before then, give us a call.

Insect Trap Count Averages at the NWMHRS
 

Date	Codling Moth	Spotted Tentiform Leaf Miner	Lesser Peach Tree Borer	American Plum Borer	Oblique Banded Leafroller	Grape Berry Moth
5/18	0	660	8	30
5/24	1	88	1.3	14.3	0
6/1	0.6	85	17	4.6	0	9

Please send any comments or suggestions regarding this site to: 
Bill Klein, kleinw@pilot.msu.edu

Last Revised:6-1-99