July 25, 2000

GROWING DEGREE DAY ACCUMULATIONS through July 24th at the NWMHRS

Year          2000      1999      1998      1997
GDD42    2002       2247       2264     1754
GDD50    1193       1449       1444     1094

GROWTH STAGES:
Pear: Bartlett -- 39mm
Apple: Red Delicious -- 57mm
Tart Cherry: Montmorency -- 22mm
Grapes: Chardonnay -- berries touching

WEATHER
By Jim Nugent

Drought conditions have continued to get more severe in NW Michigan.  At the NWMHRS rainfall this past week amounted to 0.11", while evaporation totaled 1.16". Evaporation exceeds rainfall by 1.05" for the week and by 13.21" for the growing season.

Evaporation and rainfall rates at the NWMHRS are as follows (for irrigation scheduling purposes we have included the 75% of evaporation vs rainfall calculation):

	Evaporation	Rainfall	Evaporation less Rainfall	75% of Evaporation	75% Evaporation less Rainfall
Past 2 weeks	3.19	0.16	3.03	2.39	2.23
Past 4 weeks	6.23	0.56	5.67	4.67	4.11
Since May 1	17.12	6.51	10.61	12.84	6.33

PESTS AND DISEASES
By Gary Thornton, District Fruit IPM Agent

Tart cherry growers only need to be worried about controlling cherry fruit fly if harvest is more than four or five days away and if they are above threshold. Cherry leaf spot pressure continues to be low. Post harvest sprays can go on now for blocks that are finished with harvest, however, it is debatable whether or not one is needed where control has been excellent. Growers should keep in mind that harvest ended early this year. Two spotted spider mites are at low levels in tarts, but growers should watch closely for increasing numbers if the dry weather continues. Plum nursery mite populations are high in some tart cherry blocks, giving those blocks a brownish cast to the foliage (not "bronzed", as with spider mite damage). High mite populations of either Eriophyid or spider mites, when combined with serious water stress, often lead to "firing" of limbs in tart cherries.

Codling moth is between generations, however, apple growers may have to treat now if their trap catches were above threshold in the last few weeks. Apple maggot emergence has been slow, with very few showing up in commercial blocks to date. Some apple and plum blocks are above threshold on mites. Spotted tentiform leafminers are in the sap feeding stage. Green apple aphids are common, but predators are common, also. 

Peach growers should be controlling brown rot on early varieties. Even with dry weather fungicides will improve shelf life after harvest.

Pear psylla pressure has been high this year. Sucker growth is slowing, and thus the ideal feeding sites are declining in number. If growers are still seeing high nymph numbers, then an additional control may be needed.  All stages of pear psylla exist now.

MISCELLANEOUS

Tart Cherry Update
By Jim Nugent

• Mira Danilovich, West Central District Horticulture Agent, reported this morning that the crop in West Central Michigan is picking long.
• Be sure to apply for diversion credit for blocks that do not get harvested due to quality problems or lack of yield. 
• Reminder that diversion credit is also available for partial blocks, if crop is diverted in whole rows from either side of a block.
If you are interested in the weekly CIAB raw product report, you can access it at CIAB's website: www.cherryboard.org

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

Last Revised:7-25-00