1. Freeze Protection in European Pear 2008 Kitren Glozer Department of Plant Sciences, UC Davis Rachel Elkins UCCE, Lake & Mendocino Counties

2. Flower buds and cold hardiness  Cold hardiness is reduced by –low chill accumulation –cycling warm and cold periods in dormant season –Delayed entry into dormancy –poor nutritional status  Buds ‘at risk’ have poor vascular connections, lower sink strength, low nutrient status and PGR production

3. 4/6 4/7 3/26 Dates of Treatment = tight cluster & 10-20% bloom Killer Freeze Post Petal Fall

4. Cropload rated May 15, after final fruit drop. Application dateRating ProGibb + Promalin + BlightBanApril 62.0 a ProGibb + PromalinApril 61.4 ab BioForgeMarch 261.0 ab ProGibb + Promalin+ BlightBan 2xApril 6 & 70.8 b ProGibb + PromalinMarch 260.75 b ProGibb + Promalin 2XApril 6 & 70.6 b ProGibb + DithaneMarch 260.6 b ProGibb + Promalin + BlightBan, before freezeMarch 260.4 b Untreated control0.4 b BlightBanMarch 260.2 b Whole tree treatments, mistblower, 100 gpa, Breakthru penetrant with all but BioForge

5. Most promising results after April 20 freeze ProGibb (GA 3 ) + Promalin (GA 4+7 ) with BlightBan @ early bloom ProGibb + Promalin @ early bloom BioForge (2% N from urea, 3% soluble potash K 2 O) – only timing tested was @ tight cluster ProGibb + Promalin @ tight cluster Most of crop was lost to late freeze Return bloom and yields from 2008 treatments will be evaluated in 2009 Trial will be repeated in 2009

6. Acknowledgements Our appreciation to our grower-cooperator and to the California Pear Advisory Board for ongoing support