FruitNet Weekly Report | Publications | Northwest Michigan Horticultural Research Station

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Nikki Rothwell
District Horticulturist

District Fruit IPM Agent

Bill Klein
Farm Mgr, NWMHRS

Duke Elsner
Agricultural & Regional Viticulture Agent

Leelanau Extension Director

April 24, 2007

GROWING DEGREE DAY ACCUMULATIONS THROUGH APRIL 23 AT THE NWMHRS:

Year	2007	2006	2005	2004	2003	2002	17yr. Avg.
GDD42	192	247	258	156	148	179	155.4
GDD50	76	107	113	54	61	96	61.5

Growth Stages at NWMHRS (4/23/07—8:00am)

Apple: Early Tight Cluster
Pear: Bartlett: Late Bud Burst
Sweet Cherry: Hedelfingen: Green Tip: Gold and Napoleon: Bud Burst
Tart Cherry: Montmorency: Green Tip; Balaton: Early Bud Burst
Apricot: 25% Bloom
Plum: Bud Burst
Grapes: Chardonnay: Scale crack

WEATHER

The weather was very warm this past weekend with Sunday reaching into the 80’s. The temperatures cooled down to more April-like on Monday, and the rest of the week will follow suit. We have moved along in phenological development: tart cherries are at green tip, sweet cherries are at green tip to bud burst, Balatons are at early bud burst, and apples are at early tight cluster.

Crop Report

Tree Fruit: The damage in the northwest still seems a bit too early to call for an overall estimate. At this time, we have reported some damage in tarts and sweets, but it does seem to be spotty throughout the region. If the weather continues to cooperate and we have good pollination conditions, we anticipate a good crop in the region.

Grapes: Some bud mortality occurred as a result of the April freeze, but overall NW vineyards did not suffer badly from that weather event. Bud death in winter due to poor can maturation and powdery mildew infection is significant in some vineyards. Bud swell is just underway; most producers have completed pruning and tying. Growers planning on dormant sprays for disease control need to get these applications on soon. No pest insects have been seen to this point, although beneficials such as lady bugs and spiders have been seen in vineyards, and honeybees are collecting sap from pruning cuts.

There will be a series of "first Friday" grape IPM meetings this summer, from 3-5pm on May 4, June 1, July 6, and August 3. Locations will be selected based on where problems develop in area vineyards and will be announced via the FruitNet and newsletter.

Pest Report

Tree fruit: With this recent wet weather, a few stations in the region have reported low infection levels for apple scab. East Leland, Kewadin, Northport, Benzonia, the NWMHRS areas all had enough moisture and warm temperatures to initiate an apple scab infection period.

Insects: We have observed low levels of apple rust mites, two-spotted spider mites, and green apple aphids in apple.

Important pesticide reminders
Nikki Rothwell, District Horticulturist
Codling Moth Control Materials

I know many growers are looking for a way to curb costs for codling moth control, especially those where Guthion is not an effective option. Lorsban and Lannate are the two products that come to mind for economical control chemistries. I have also received many questions regarding these products, and here are my recommendations. Lorsban works extremely well, but the problem these days is timing; this product is not to be used after bloom, which limits effective use of Lorsban. I do not recommend pushing the limit of timing for this product. Lannate is a chemistry that had some efficacy against codling moth, but if an orchard has reported any amount of organophosphate resistance, Lannate typically wears out much faster than Guthion. In a nutshell, these products may be cost effective, but timing and efficacy are both considerations when making codling moth control decisions.

Important Guthion Reminder

As all of you know, Guthion has new restrictions on its use. This insecticide is only labeled on apples, pears, cherries, and blueberries. Guthion does not have a label for peaches, apricots, grapes, or plums. The 2007 Michigan Fruit Management Guide has two mistakes where it says Guthion is still an option on peaches and plums: THIS INFORMATION IS INCORRECT! Guthion cannot be used on these crops. Another reminder is that if the crop is NOT on the label, a grower CANNOT use Guthion. This rule is different than in the past, and currently there is NO allowable Guthion residue on crops that have been dropped from the label (peaches, apricots, plums, grapes).

The total amount of product allowed per acre is as follows: apples @ 8lbs./acre, cherry @ 3lbs./acre, and pears @ 6lbs./acre. PHI’s for apple and pear is 14 days, and 21 days if last application is >2lbs. Growers must observe a 60ft buffer from permanent bodies of water, and they must observe 60ft buffer from occupied dwellings, which does not include farm buildings and barns. Please call the research station if you have further questions (946-1510).

Neonicotinoid Follow-up on CCD

As we mentioned last week, we have reported cases of colony collapse disorder (CCD) in our honeybee hives in the region. We also reported that neonicotinoid insecticides have been found in nectar and pollen in hives where bees have disappeared. The following recommendation has been issued from Dr. Zachary Huang, the MSU honeybee expert: Avoid using neonicotinoid insecticides near honeybees, if possible. If growers must rely on these chemistries, avoid using them during bloom or before bloom, as the pesticides are systemic and can be transported into nectar and pollen. As we do not use these insecticides around bloom time in cherry, this recommendation can be easily followed. In the case of apples, we recommend other chemistries that are more effective for first generation codling moth and obliquebanded leaf roller control when we would have potential contact with honeybees. Recent evidence suggests neonicotinoids can impair honey bee learning and disrupt their homing abilities.

Mustang Max Label on Grapes

Another new pyrethroid has been labeled for grapes this season. Mustang Max is also labeled for berry crops, including blueberries. We currently do not have much efficacy data for this product, and we anticipate having more information for growers by next season. Mustang Max is labeled for control of leafhoppers in grape and leafrollers and root weevils in berry crops.

Bacterial Canker Reminder

Sweet cherries here at the NWMHRS have reached green tip while other varieties are at budburst. If growers are planning to put on copper applications, they need to think about doing so soon. As we are in the pre-bloom stage (not dormant stage anymore), copper rates should be reduced to 25-35% of the dormant rate (dormant rate = 1.2-2lbs of metallic copper with either one pint of spray oil per 100 gallons of water or 6-9 lbs of hydrated lime per acre). Sweet cherries are very sensitive to copper applications, so make sure to safen the tank with spray oil or lime, and do not apply copper products any later in the season than white bud to avoid phytotoxicity.

Insect and disease predictive information is available at:
http://www.enviroweather.msu.edu/home.asp

This issue and past issues of the weekly FruitNet report are posted on our website at: http://www.maes.msu.edu/nwmihort/faxnet.htm

ACTUAL AND PREDICTED DEGREE-DAY
ACCUMULATIONS SINCE MARCH 1, 2007

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

Last Revised: 4-24-07