Tree Fruit Development- In most locations this week, peaches are in bloom to petal fall, pears in bloom, apples are in various stages of bloom depending on variety and location in state.  The warm weather this past week pushed development along very quickly!!  However, we also experienced frost this week in some locations, particularly on Monday morning (May 7).  The lowest temperature at my weather station sites was 29 degrees at 6AM on May 7 in Lebanon, CT. 

New England Tree Fruit Pest Management Guide – We have received our copies of the New England Tree Fruit Pest Management Guide.  They are available for $35 (includes shipping & handling) from the UConn Communications and Information Technology Office; Unit 4035; 1376 Storrs Rd.; Storrs, CT  06269 or (860)486-3336.  As I’ve mentioned before, this guide includes apples, pears and stone fruits. Those of you who purchase the guide can also get access to the on-line version.  You will need to contact me for the password for this access.

Insect update-  Traps are up for tarnished plant bug (low, white sticky traps), apple blotch leafminers (low, red sticky traps) and European apple sawfly (high, white sticky traps).  Tarnished plant bug captures have been very low overall,  leafminers counts have been variable.  European apple sawflies started to emerge this week. 

Apple Scab Status – I now have weather stations at 7 orchard locations throughout the state.  Below is this week’s summary for 4 of them which includes the location, date weather data was downloaded, dates when apple scab infections occurred since green tip, percent spore maturity and the degree days for apple scab development.  The degree days for apple scab are calculated with a base of 32 degrees and start at 50% McIntosh green tip in each location.  This occurred on April 20 in South Glastonbury and April 21^st in the other locations.  Note that the “accelerated” phase of apple scab occurs between approximately 300 to 700 degree days (DD). This is the time when most of the apple scab ascospores mature; therefore; the critical time for scab treatments.  

The weather stations checked on Thursday (May 10) showed scab spore maturity at 53% (462 degree days) in Lebanon, CT and 39% spore maturity (389 degree days) in East Lyme.  It looks like that coastal climate (and fog!) in East Lyme is keeping it a little cooler. 

There had been no rain this past week until this morning; therefore, I did not expect any infection periods.  However, note that there was a wetting period sufficient for an apple scab infection that started at 11PM on May 9 at the East Lyme location.  Temperatures were very warm that night and coastal areas (near Long Island Sound) were socked in with fog.   When I visited the orchard on May 10, leaves were still wet at 10:30AM.  The good news is that the wet period began at night so there is a lower chance of a significant spore release.

Summary of Apple Scab Data throughout the State

 

South Glastonbury- May 5th

• Scab Infections since green tip- 4/26, 4/27, and 4/28
• Spore Maturity- 43%
• Degree Days- 407

 Pomfret – May 5th

• Scab Infections since green tip- 4/27,4/28, and 4/29
• Spore Maturity- 36%
• Degree Days- 372

East Lyme – May 10th

• Scab Infections since green tip- 4/27, 4/28, 4/30, and 5/10 (fog and dew)
• Spore Maturity-39%
• Degree Days- 389

*Note: The Apple Scab infection on 5/10 was indicated by two of the three computer models that we use with our Spectrum weather stations.  The Washington State model indicates a light infection, and the Cornell model also indicates an infection.  Also note, the wet period began at night (11PM on 5/9/07) so there is a lower chance of a significant spore release.

 Lebanon- May 10th

• Scab Infections since green tip- 4/27 and 4/28
• Spore Maturity- 53%
• Degree Days- 462

 

Fire Blight-  The following information is from Jon Clements, UMass.  Connecticut conditions at this time are very similar to Massachusetts.  The computer models I ran also indicated a high risk for fire blight Thursday night (May 10) and today (Friday, May 11) if rains occurred. 

With open bloom, warm temperatures, and the chance of rain, the threat for fire blight is significant through tomorrow, Friday (May 11). If you had fire blight in orchard blocks the last couple years, or in the immediate area, or have susceptible cultivars on dwarf rootstocks (Gala, Honeycrisp, Fuji, Paulared, Gingergold, maybe even Cortland on

M9 or M26), or pears, a streptomycin application today (Thursday), before the rain, is probably a very good idea. Keep in mind streptomycin works only when applied within 24 hours before or after the wetting event. 

It works best when applied before. Note that even the moisture from a spray application or heavy dew is considered wetting. 

The rate of Agrimycin-17 is 0.5 lb per 100 gallons dilute plus one pint of Regulaid. The strep can be concentrated, but not the Regulaid. 

I am posting the results of actual and forecast weather data entered into the Maryblyt and Cougarblight fireblight models through tomorrow on the UMass Fruit Advisor: 

http://www.umass.edu/fruitadvisor/hrcweather/2007/fireblight.txt 

Note that an EIP above 100 is considered a risk for fire blight infection, as well as all the steps have been met in the Maryblyt model. The Cougarblight model suggests there is a high to extreme risk of infection.