Wines & Vines Home
Welcome Guest

Does Nitrogen Cause Pinot Leaf Curl?

Researchers analyze mystery ailment at Sonoma County Grape Day

by Andrew Adams
Pinot Leaf Curl
Pinot Leaf Curl, a disease that can cause stunted leaf development and even kill shoots and nodes, has been striking Pinot Noir, Pinot Blanc and Pinot Meunier vines with greater severity in recent years. Photos from Rhonda Smith
Santa Rosa, Calif.—In the past three years, the vine sickness Pinot Leaf Curl has struck more often and with greater severity in Sonoma County’s valuable Pinot Noir vineyards.

The ailment also can affect Pinot Blanc vines and has been observed less frequently in Pinot Meunier. Pinot Leaf Curl, or PLC, appears during spring; symptoms can range from stunted or distorted leaf growth to severe instances in which an entire shoot and node can die.

Rhonda Smith, University of California extension advisor for Sonoma County, made the ailment a focus of Sonoma County Grape Day on Feb. 16. She said she wanted to draw attention to the sickness and explore a possible relationship between the disease and nitrogen. She said the disease, which has been found in every Pinot Noir region of California, is known to be more common during cold, wet springs.

Dr. Doug Adams, a professor of viticulture with UC Davis, joined Smith on the panel. Adams said that when vines enter dormancy, they store nitrogen to support growth in the coming spring and summer. When the growing season arrives, the plants convert the stored nitrogen into a form that can be metabolized by the plant. The nitrogen compounds used during this process can also yield putrescine. Elevated levels of putrescine can be toxics to vines, he said.

Is putrescine the culprit?
The next step, Adams said, is to find a 100% asymptomatic Pinot vineyard and determine “normal” levels of nitrogen compounds. Then researchers can evaluate if symptomatic tissues contain elevated levels of putrescine. “You can find putrescine in most plants, but only in trace amounts,” Adams said.

Various terms have been used to describe PLC. Smith said the condition was known, but it has not been a major problem until recent years, when Sonoma County growers began to become concerned by the increased incidence and severity of symptoms.

Smith said the condition can reduce crop loads, but it was hard to discern how much of an effect it may have had on the 2011 harvest totals because of losses from botrytis and other, more common pests.

Smith also wanted to draw growers’ attention to the fact that while PLC can sometimes look like botrytis, it is a wholly separate condition. She said PLC first weakens tissue, and then opportunistic botrytis finds a way to attack the vine. Therefore, Smith stressed that fungicide applications do not work on PLC.

There appears to be some variation in clonal susceptibility for PLC: When present in a vineyard, the condition tends to be found in mature blocks, and mild symptoms can occur in up to 80% of vines, Smith said.

Symptoms to watch
According to a report written by Smith, symptoms of PLC can range from mild to severe. Onset occurs early in the growing season, most commonly when three or more leaves separate from the shoot tip. The leaves then appear to “bend or fold downward across the middle of the blade, perpendicular to the main vein”—hence the descriptive “leaf curl” name. The vines will appear to have “broom-like growth” with multiple lateral shoots pushing at all nodes, with abnormal leaves until a single lateral becomes dominant.

Mild symptoms are often limited to darkened or necrotic regions on the underside of leaves. In a severe case of PLC, the necrotic region will extend to the petiole: Both the blade and petiole abscise from the shoot. If that is a cluster-bearing node, the disease can reduce crop load.

Sonoma Grape Day is an annual event for grapegrowers, organized by UC Cooperative Extension and sponsored by the Sonoma County Winegrape Commission.

Currently no comments posted for this article.

Wines & Vines Home
866.453.9701 | 415.453.9700 | Fax: 415.453.2517
65 Mitchell Blvd., Ste. A San Rafael, CA 94903
Wine Industry Metrics
Off-Premise Sales
IRI Channels »
Month   12 Months  
October 2015 $604 million
$8,267 million
October 2014 $572 million $7,790 million
Direct-to-Consumer Shipments » Month   12 Months  
October 2015 $288 million
$1,919 million
October 2014 $284 million $1,751 million
Winery Job Index » Month   12 Months  
October 2015 179
October 2014 139 226
MORE » Released on 11.13.2015


Direct To Consumer
Wine Shipping Report
Download full report »

Practical Winery & Vineyard Library
Search the PWV archive »

  • December 2
    2015 UC Davis Grape Day
  • December 3
    North Coast Wine Industry Expo
  • December 5-6
    Holidays in the Vineyards
  • January 13-14
    DtC Wine Symposium
  • MORE »

Article: Kronenberg Leaves Legacy of DtC Opportunities »
This is amusing. While I do not quarrel with Paul's many contributions over the years,...
Reader: Guest
Article: Kronenberg Leaves Legacy of DtC Opportunities »
Wow! This this a re-writing of history! As a founder and namer of Family Winemakers...
Reader: Guest
Article: Can Wine Grapes Be Grown Without Chemicals? »
It sounds like your problem is with semantics, not with the application of products to...
Reader: Carol Collier
Article: Cuvaison Upgrades to Second Generation of Pellenc Sorter »
I'd like to know what they are doing with the sorted stuff, especially the first...
Reader: Matthew Delicata
Article: Growers Suffer Low Yields in Paso Robles »
This year's Paso Robles/San Miguel "mature" Cabernet Sauvignon yields were down to 30% of normal while...
Reader: Guest

2016 Directory/Buyer's Guide
The Wines & Vines Directory and Buyer's Guide
Wines & Vines Magazine
Digital Edition Now Available!
Wines & Vines Digital Edition Now Available
The Wines & Vines Online Marketing System
The Industry Standard winery marketing application
Latest Job Listings
 Referral Marketing Opp...
 Northeast, NA
Sales and Marketing
 Marketing & Communicat...
 Rutherford, CA
Sales and Marketing
 Assistant Tasting Room...
 Paso Robles, CA
DTC, Tasting Room and Retai
 Account Coordinator
 American Canyon, CA
General Administration and
 New World-Class Restau...
 Philo, CA
General Administration and
 Compliance Administrat...
 Healdsburg, CA
General Administration and
 Tasting Room Manager
 Santa Rosa, CA
DTC, Tasting Room and Retai
 Sales Representative
 Miami, Ft. Meyers/Naples, Tampa, FL
Sales and Marketing
 Area Sales Manager
 New York City (Metro), NY
Sales and Marketing
 Wine Adviser
 Norwalk, CT
Sales and Marketing
More Job Listings >>
Follow Us On:

Home  |  About Us  |  Editors  |  Subscribe  |  Print Edition  |  Digital Edition

Advertise  |  Site Map  |  Contact Us  |  Privacy Policy
Copyright © 2001-2015 by Wine Communications Group, Inc. All Rights Reserved.
No material may be reproduced without written permission of the Publisher.
Wines&Vines does not assume any responsibility for any unsolicited manuscripts or materials.