Wines & Vines

144 WINES&VINES Collector's Edition GRAPEGROWING WINE EAST problem within the VitisGen2 project at Cornell AgriTech, the powdery mildew team has devel- oped highly controlled laboratory assays to assess powdery mildew resistance. This is how we do it: Rating resistance in the field. The traditional approach is to allow natural infection of vines (grown with no fungicides) and then to subjectively estimate the severity of disease infections on each vine, typically by using a 4- or 5-point rating scale. However, field ratings are subject to many uncon- trolled variables that affect how accurate and precise results are. Powdery mildew inoculum, though ubiquitous, is not evenly distributed throughout the vine- yard, or even within vines, and field populations of the pathogen have their own genetic variability. It almost goes without saying that temperature, solar radiation and rainfall vary from season to season and moment to moment, affecting disease severity and the lighting conditions needed to record rat- ings accurately. Rating resistance in the laboratory. Laboratory-based phenotyping offers scientists many advantages over field-based disease ratings, including the abil- ity to control the environment, the genetics of the pathogen and the quantity of pathogen spores that land on the leaf. In our laboratory, we use leaf disks and inoculate them with a suspension of spores. After incubation, we then remove the green chlorophyll and stain the fungus dark to count the num- ber of fungal hyphae that intersect with a microscope grid (Figure 2). This standard procedure elimi- nates much of the environmental "noise" in field evaluations, re- moves human bias and subjectiv- ity, and allows us to replicate tests of each vine on several disks. By doing so, we can identify more moderate forms of resistance that would be difficult or impossible to detect in the field. Automating the process. Ex- amining and scoring leaf disks is still a time-consuming, tedious task. With 200 siblings to evalu- ate, tissue from four shoots and duplicate leaf disks for each shoot, each evaluation involves examin- ing 1,600 leaf disks, which re- quires three to 12 weeks of staff time spent on physically exhaust- ing and repetitive microscopy. This is one reason why we've de- veloped a robotic evaluation tool that uses live sample imaging to quantify the hyphae in each sam- ple. Our automated process can capture ratings for the same 1,600 leaf disks in one day, delivering results 20- to 80-fold faster than manual microscopy, and with much less pain (Figure 3). This imaging of living samples and increase in efficiency means we can rate the individual leaf Firgure 3: Automated powdery mildew phenotyping setup uses image analysis and inoculated leaf disks to rate powdery mildew resistance. - B E C O PA D - Y E A S T & E N Z Y M E S - C R U S H PA D E Q U I P M E N T - S T E R I L E F I LT R AT I O N - W I N E R Y H O S E - O A K A LT E R N AT I V E S EASTERN WINE LABS Serving the Analytical needs of East Coast Wineries WWW.EASTERNWINELABS.COM Ph 609-859-4302 Cell 609-668-2854 chemist@easternwinelabs.com AOAC Member EasternWineLab_Mar09.qxp 1/22/09 9:47 AM Page 1 Basic Hoe comes with a Hillup and a Takeaway Blade. Additional attachments include .3 Tooth Cultivator, Undercutter Blade, Rotary head, " NEW " Rolling Cultivator and "Vine Auger". The Green Hoe Company, Inc. 6645 West Main Road, Portland, NY 14769 PHONE (716) 792-9433 FAX (716) 792-9434 WWW.GREENHOECOMPANY.COM GREEN GRAPE HOE

• Cover