Downy Mildew in Onions

Conditions right now are perfect for downy mildew and botrytis.  High humidity, heavy dew and warm temperatures are creating perfect growing conditions for the pathogen.

For information about fungicides registered for use on onion in Nova Scotia please see the Onion Management Schedule.

Watch for Tomato Diseases

Tomato Leaf Mold

 
Due to a wet growing season the tomato crop, especially in high tunnels, has been infected by leaf mold. Some growers experienced difficulties associated with leaf mold in June while others are getting their crop infected now.

Tomato leaf mold is caused by Fulvia fulva (also known as Cladosporium fulvum).  This fungus attacks during cloudy, humid weather and can be particularly severe in plastic greenhouses.  We certainly have had weather that would favour this pathogen.

 
Tomato leaf mold can spread very quickly under humid conditions such as we have been experiencing lately.  It is key (even more important than fungicides) to increase air flow through the crop and to lower the humidity.  It is advisable to crack the vents at dusk and increase night-time temperatures so that they are above outdoor temperatures to prevent high humidity in the greenhouse. 

Heat during rainy days might also be required.  Pruning off the lower leaves will help to get air flow through the crop and reduce infection.  Air movement with fans is also a good idea.  If the infection is serious and the crop is nearing the end of production, it might be best to harvest what you can without investing more money/effort in control. 

There are not many fungicide choices.  Fontelis and Pristine are registered for Cladosporium suppression on other crops, but both fungicides are also registered on tomato for Botrytis and Alternaria control.

Early blight, botrytis and septoria have all been found in tomato crops.  Given warm, humid weather it is likely that before too long we might see late blight on tomatoes.  In addition to proper canopy management, pruning out the diseased foliage and proper ventilation, it may be necessary to keep ahead of diseases by providing periodic fungicide applications.  For more information please see the Tomato Management Schedule - a guide to weed, insect and disease management in tomatoes.

Garlic and Onion Diseases

I wrote about white rot and its risk to garlic industry in Nova Scotia. That threat is still real and growers should be using only seed from clean seed program.

Aside from white rot, there are other garlic diseases which can be devastating to garlic crop, namely botrytis and downy mildew. I have already seen some heavy botrytis disease pressure in commercial garlic crop plantings. Warm and humid weather is very conducive for disease development.

Botrytis and downy mildew are serious crops of onions and growers must apply fungicides to keep those diseases to the minimum.

For registered fungicides in garlic please visit: 
http://www.agrapoint.ca/Pest%20Management%20Guides/Vegetables/2012/Garlic%202012.pdf

For registered fungicides in onion crop please visit:
http://www.agrapoint.ca/Pest%20Management%20Guides/Vegetables/2012/Onion%202012.pdf