Mildew Resistant Basil
Answered by: Conrad Richter
Question from: No Name Given
Posted on: December 07, 2004

On Tue, 7 Dec 2004 contact@pitchfruits.ch wrote:

I would like to know if you have seeds of basil, large-leaf variety which is resistant with the mildew. We use more and less 100 kg every year.

An occurence of downy mildew on Genovese basil in Italy was reported in 2004 (Garibaldi, Minuto, Minuto, and Gullino, 2004. Plant Dis. 88:312; http://www.apsnet.org/pd/searchnotes/2004/1223-02N.asp). In that report, the fungal pathogen was identified as a species of Peronospora. Peronospora, including P. lamii, was reported to have infected sweet basil in Uganda in 1933.

We are not aware of any systematic trials of basil varieties and their resistance to mildew. No currently available varieties are known to be resistant or tolerant of downy mildew.

The main control recommendation is preventive. The disease proliferates in cool, humid conditions, especially at night. Typically, infections occur when night time temperatures are below 24 degrees Celsius and the relative humidity is high enough for dew to form on the leaves and remain for at least 3 hours. Typically, the spring and fall seasons are when downy mildew is most likely to occur on basil.

Preventative strategies include: 1) avoiding overhead irrigation, or if it is used, to irrigate early in the day; 2) increasing ventilation in greenhouse crops; 3) maintaining greenhouse crops at about 25 degrees Celsius at night; 4) rotating crops, with at least 3 year intervals between basil crops.

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