Central Coast Vineyard News    

 

Date:  April  10,  2015  

Pinot  Leaf  Curl  

Pinot  leaf  curl  (PLC)  is  a  physiological  disorder  that  affects  the  Pinot  cultivars.  The  symptoms  are  general   seen   in   the   coastal   production   areas   during   cool   spring   temperatures.   During   the   cool  spring   temperatures  of  2010   symptoms  of   this  disorder  were  very   common   to  Pinot   vineyards.  This  week   I  have  had  several   reports  of   this  disorder   showing   in  Pinot  vineyards   in   the   central  coast.  

Symptoms  

Symptomatic   leaves   on   elongating   shoots   curl   downward   across   the   middle   of   the   leaf   blade,  perpendicular  to  the  mid-­‐vein.  The  angle  of  the  downward  bend  is  acute;  the  marginal  tip  of  the  center   lobe   may   come   into   contact   with   the   petiole.   Mild   symptoms   involve   only   the   blades;  continued  expansion  of  which  results   in  a  misshaped  and  reduced  leaf  size.    A  necrotic  region  is  present   on   the   mid-­‐vein   preventing   further   elongation.   If   the   necrosis   expands   to   include   the  petiole,   the   leaf  will  abscise   from  the  shoot.  Severe  symptoms  occur  when  necrosis   involves   the  node  at  which  a  leaf  abscised,  killing  the  shoot  distal  to  that  point.  

Symptoms  appear  somewhat  similar  to  Botrytis  shoot  blight  caused  by  Botrytis  cinerea  on  foliage  under  cool,  wet  spring  conditions.  In  the  past  samples  of  PLC  affected  tissue  have  been  tested  and  no   known   foliar   pathogens   have   been   associated   with   the   samples.   Fungicide   applications   are  unwarranted  and  will  have  no  effect  on  subsequent  PLC  symptom  development.  

Research   conducted   by   Rhonda   Smith,   UCCE   Sonoma   County   and   Doug   Adams,   Department   of  Viticulture  and  Enology  UC  Davis,  have  shown  the   level  of  putrescine  were  found  to  be  elevated  in  symptomatic   versus   asymptomatic   samples.   Relative   amino   acid   levels  were   less   clearly   aligned  with  symptoms;  symptomatic  blades  were  associated  with  elevated  gluatamine  levels  in  addition  to  elevated   putrescine.   Glutamine   is   the   predominate   amino   acid   in   vine   sap   and   the   main   amino  transport   form  of   reduced  nitrogen   in   the  vine.  With   the  current   information,  pinot   leaf   curl   is  a  physiological   disorder   most   likely   associated   with   elevated   nitrogen   levels.   Elevated   putrescine  levels   are   toxic   to  plant   tissue   and   are   thought   to  be   involved   in   symptom  development   in   false  potassium   deficiency   (“spring   fever”)   and   early   bunch   stem   necrosis.   Pinot   leaf   curl   may   be   an  additional  disorder  associated  with  putrescine.  

 

Source:  Adapted  from  UCCE  Sonoma  County  (http://cesonoma.ucanr.edu/viticulture717/Viticulture_Publications/)  

 

 

The  above  two  pictures  show  leaf  symptoms  associated  with  pinot  leaf  curl.  Note  the  necrotic  areas  on  the  petiole  and  base  of  the  leaf  veins.  

 

 

 

Note   the   progression   of   the   dark   necrotic   tissue   forming   in   the   upper   picture   (red   arrow)   and  increasing  in  the  other  picture  in  the  apical  end  of  the  petiole  and  the  base  of  the  main  leaf  veins  of  these  Pinot  noir  leaves.  

   Larry  Bettiga  

Viticulture  Farm  Advisor  for  Monterey,  San    Benito  and  Santa  Cruz  Counties.  lbettiga@ucanr.edu    1432  Abbott  Street  Salinas,  CA  93901  831-­‐759-­‐7361  phone  831-­‐758-­‐3018  fax    Central  Coast  Vineyard  News  is  produced  by    Larry  Bettiga.    

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