Biosecurity is important in horticulture crops too!

Biosecurity, often thought of as a livestock issue, is important in horticulture crops too.  The old adage "an ounce of prevention is worth a pound of cure" is very true for horticulture biosecurity risks, especially since many issues don't have viable solutions.  Equipment can carry soil-borne pests like clubroot, Verticillium wilt, and nematodes from field to field.  The more soil that gets transported between sites, the higher the risk of infection from these soil-borne pests.  Diseases such as downy mildew, late blight, and angular leaf spot can be inadvertently carried on clothes, boots, and gloves.  Difficult to control weeds such as yellow nutsedge can also be carried from field to field on equipment.

Clubroot can be transmitted on equipment, boots, and eroding soil

Important biosecurity management steps are first to make sure that these diseases and pests don't come on to the farm.  If you know you already have problem areas, takes steps to manage and contain them so that it doesn't spread to the rest of your fields.  Manage your culls and plant certified disease-free seeds and root stock.

To read more about biosecurity risks and how to manage them, check out Perennia's Horticulture Biosecurity Fact Sheet.

Downy mildew in lettuce

Downy mildew was found in a lettuce field in the Valley this week by Erika Bent (APM Agricultural Pest Monitoring Cons. Ltd.).  We don't always see lettuce downy mildew (Bremia lactucae Regel), but it can be very destructive. Spores are spread via splashing water or wind.  Air currents can carry spores several kilometers.  Cool temperatures (between 15' and 21' Celsius) are conducive to disease development, especially under wet conditions.  This includes heavy dew set in the mornings and overhead irrigation. 

Infection usually starts in the older leaves and travels inward.  Pale green or yellow areas will become apparent on the upper surface of the leaves, often having an angular appearance, with sporulation occurring on the underside.  This infection can spread very quickly, especially under favourable growth conditions, so be sure to check your fields often!

Fields that have been recently harvested are ideal locations for disease buildup to get out of hand, so be sure to plow down lettuce residue.

There are numerous fungicide options, which can be found on the Perennia Lettuce Management Schedule. Downy mildew can build up resistance to pesticide group modes of action very quickly, so be sure to rotate between pesticide groups at every application. While there are varieties that have been bred to be resistant to downy mildew, due to the quickly evolving nature of this disease, varieties may not be resistant to all strains of downy mildew.

Powdery Mildew in Cucurbits

With the arrival of cooler nights and heavy night dews, conditions are right for powdery mildew to thrive.  As a matter of fact this year it has been seen on a number of crops earlier than usual due to wet weather.  The disease appears on leaves as a white powdery mass composed of the spore-bearing structures of the fungus.  The disease can affect entire fields.  Severely infected leaves shrivel and die. The fungus can also grow on petioles and young stems.  Infected plants are yellow and stunted. Pictures of powdery mildew in cucurbits can be found here .

Fruits are not attacked, but are usually small and deformed.  The spores are air-borne.  Resistant cultivars exist.  Preventative fungicide applications will effectively control powdery mildew.  For more information on fungicides registered for control of powdery mildew in cucurbits see the Pumpkin & Squash Management Schedule – a guide to insect, weed and disease management.