Notes on the 2014 Tomato Blight

On July 5th, 2014 the 1st named storm of the 2014 Hurricane season, Arthur, tore through Nova Scotia uprooting trees and leaving 144,000 residences and businesses without power. It was a bit of nasty surprise so early in the season.
Unfortunately for Nova Scotia farmers and gardeners there was yet another nasty surprise to come.
The thrashing winds and heavy rain had created the perfect conditions for a severe outbreak of ‘Late Blight’ decimating tomato and to a lesser extent potato crops across the province.
Late Blight, Phytophthora infestans (plant destroyer) is a mold pathogen that primarily attacks members of the Solanaceae plant family, including commercially important species such as tomato, potato and peppers. It was an outbreak of P. infestens that triggered the Great Irish Potato Famine that claimed over a million lives and the forced emigration of millions more. And on an even more sinister note P. infestens has in the past been the object of considerable research as a potential biological weapon to destroy critical food stocks in times of conflict.
The spores of late blight mold are dispersed by wind and water action to eventually settle on the moist, humid surfaces of plant leaves and stems. Early signs of infection are grey/green water soaked spots that enlarge over time turning brown and firm. Most years the spore dispersal occurs somewhat later in the season and while plants are affected, a complete crop loss is rare. In 2014 however the damaging winds of Arthur resulted in a much different outcome, with many small tears and abrasions, plants were susceptible to multiple points of infection and were quickly overcome.

Preventing Late Blight

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Late Blight spores while susceptible to freezing temperatures can and do survive the winter in the soil and on damaged plant leaves, stems, roots and fruit. In the case of potatoes discarded or missed tubers are often the source of seasonal reinfections.
Remove all diseased plant material from the garden and either burn it or dispose of it in your green bin. Do not add diseased plants to your compost bin, the higher temperature of the decomposing organics will facilitate spore survival over the winter and will be reintroduced to the garden when you top dress in spring.
It is important when planting to allow sufficient space between your plants for individual growth, the free movement of air and the penetration of sunlight. Overcrowding your garden creates the dank, humid conditions ideal for mold growth.
Rotate your crops. Avoid planting your tomato and potatoes in the same section of your garden each year where reinfection is likely to occur. Choose a separate bed for this year’s planting; if this is not possible consider using large containers or pots.
Stake your tomato’s and secure them as they grow to prevent wind damage; they are a vine after all and have rather weak stems.
Water your garden in the morning so the plant surfaces have an opportunity dry as the day progresses. Better still install a drip irrigation system so water is applied directly to the soil.
Applying mulch around your plants can reduce infection by controlling the spattering of spores by raindrops hitting the surface of the soil.
Spring is just around the corner so start planning your garden now. If you have any questions, concerns or comments, send them along, we always enjoying hearing from you.
Peter LaPierre
Home Harvest Kitchen Gardens

2 Responses so far.

  1. Pat Blaikiie says:

    Thanks very much for the info. We were sad to lose all the tomatoes that Gary started from seed. We weren’t going to plant them this year but have decided to plant them in pots cause WE LOVE garden fresh tomatoes.

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