WEATHER

April precipitation totaled only 1.2" at the NWMHRS, with an additional 0.24" on May 1. This is very low rainfall for the season. 

GROWING DEGREE DAY ACCUMULATIONS as of May 1st at the NWMHRS

Year          2000      1999      1998     1997
GDD42       272        271         300      152
GDD50       101        107         129        53

GROWTH STAGES:
Apricot: Harcot – petal fall
Plum: Stanley – white bud
Pear: Bartlet -- green cluster
Apple: Red Delicious - early pink
Sweet Cherry: Napoleon – 70% bloom
Tart Cherry: Montmorency – early white bud
Grapes: Chardonnay - late bud swell

COMMODITY REPORTS

Apple growers should be on the alert for spotted tentiform leafminers this year. Trap catches were averaging 870 moths per trap this last week at the NWMHRS, which is very high for northern Michigan. Egg counts are as high as 10 per leaf, which is extremely high. Provado used in early petal fall is the ideal treatment. Asana at pink is another option, but it will disrupt predator mites. The wetting period on 5/1 was not long enough to result in an apple scab infection period. Because of concerns with developing apple scab resistance to sterol inhibitor fungicides, such as Nova, Rubigan and Procure, consider incorporating compounds with alternative chemistries into the scab control program. Following are some new non-sterol inhibitor options: Sovran and Flint are two strobilurin fungicides that provide excellent scab control. Vangard is in a different class called anilinopyrimidines; it is rated as good for controlling apple scab. Vangard does not provide powdery mildew control.

Apple growers with mature trees that have had fireblight problems should consider applying Apogee between full bloom and petal fall (ideally at king bloom petal fall) for suppressing secondary fireblight infections. Apogee is a newly labeled growth regulator that shuts down growth for four weeks, starting approximately one week after application. 

Sweet cherries, plums and apricots are all susceptible to brown rot. Whenever it rains, temperatures in the 70's and high humidity create ideal conditions. Humidity after infection is extremely important in determining if the brown rot will be a threat. Tart and sweet cherries are not threatened by cherry leafspot until leaves are fully expanded. 

Please note that Vangard is not labeled for use on sweet cherries. Vangard does have a label for control of brown rot blossom blight in other stone fruits (apricot, tart cherry, peach, nectarine, plum and prune). Because Vangard is in a new class of compounds, it provides another option for delaying brown rot resistance to sterol inhibiting fungicides. Vangard does not control cherry leaf spot.

Green fruitworm trap catches remain steady. Growers interested in lesser peach tree borer disruption should be getting out their disruption ties any time between now and petal fall of tart cherries. Apricot growers should watch out for plum curculio injury. Plum growers should protect plums from black knot infection. Bravo is the ideal material, if used on a protectant basis.

MISCELLANEOUS

Sweet Cherry Pollination 
By Jim Nugent

Many blocks of sweet cherries in Michigan have been planted with the understanding that Ulster would cross pollinize Emperor Francis, Napoleon and other pollen compatible Group III varieties. This is not the case. An error in the original pollen categorization placed Ulster in Group XIII (S₂S₄ alleles). Due to observed pollination problems, researchers at Cornell University revisited the pollen classification of Ulster and found it actually to contain the S₃S₄ alleles, correctly placing it in Group III. Therefore, Ulster will not cross pollinize Emperor Francis, Napoleon, Bing, Kristin and other Group III varieties. 

If an orchard has been planted with a combination of varieties that do not cross pollinize each other, consider these options:

As a long term solution, get trees planted into the block that will provide good pollen. Call me to discuss options. For the short term, get lots of bees into the block (at least 2 hives per acre). Purchase pollen (not Bing or Lambert) to place in the hive entrance. If not purchasing pollen, then cut lots of bouquets of bloom from a good pollen variety (anything other than Group III) and place in cans with water throughout the orchard. Placing the flowers throughout the block should be more effective than placing them in front of the hives. 

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

Last Revised:5-2-00