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Designed by David Frary

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Blight resistant Tomato trial.

Trial commencing 2008 season.

Blighted Tomatoes.

For two years running now, I have lost my tomato plants to blight and it appears that I am not alone. Tomato plants are in good health and growing well, flowering, fruit starting to ripen, then within a space of a couple of weeks, they're all rotten from blight. The trouble with a disease like blight is that the worse it gets, the worse it's likely to be in following years as more and more diseased plant material is scattered about the countryside.

Sole survivor.

Having seen what happened the previous year, when the blight struck in 2007 I Immediately proceeded to cut off any infected foliage from the plants on a daily basis but this tactic only delayed their demise by a week or so. All plants quickly rotted and died except one plant that seemed to get its second wind after losing a few half-leaves and continued to ripen and develop the fruit up to the last week of October when all fruit had ripened at full size.

This one tomato plant was given to me in one of many swaps, seed from Bulgaria. The donor does not know of a variety name, just that it produces red plum-shaped fruit. As this plant appeared to have resistance to blight, the seeds were saved for this experiment. Whether the resulting seedlings will be true to type or possess blight resistance I cannot say, but with help from my friends I'm hoping to monitor 200 plants spread accross Great Britain and Europe.

Plant type.

At this stage I'm assuming the parent was not a hybrid and the flowers were not crossed with other varieties. Survivability is the primary goal here. Plants should be of vine type and grow up a string or tied to a stake with all sideshoots removed as they appear. Individual growers may modify the method as they see fit.

2008 Results.

Well, the best laid plans of men and lesser animals do not always work out quite as planned. The weather was atrocious, cold and wet and my plants all succumbed to blight as did most of the others in the trial. Enough fruit ripened though to continue with the trial and selection and with any luck eventually a superior strain will emerge.

2009 Results.

This year produced a bumper harvest but all plants had their productive life reduced by blight. My trial plants were left to grow as bush plants and survived until quite late in the season. Additionally, three other varieties were grown as cordon vines, stopped at 4 trusses and completely defoliated the moment blight was suspected. Most fruit on the vines ripened in their own time with any diseased tomatoes removed on a daily basis.

For next year, additional experiments will be carried out with other varieties and growing methods to get earlier yields. The fight goes on.

What is Blight.

Blight is a fungal disease affecting potatoes, tomatoes and to a lesser extent peppers and capsicums and spreads like wildfire throughout the country typically starting in the north spreading southwards. Once the tomatoes are infected they rot from within, rapidly developing black patches resulting in the plant collapsing in a rotten mess. This is what we are fighting against.

Blight is supposed to overwinter only in infected potatoes left in the soil but not in the soil itself, but that is only the doctrine of the UK accademia not the rest of the world. From ny observations any infected tubers rot to nothing and haulms disintergrate over the winter.

Anyway, back to tomatoes. For blight to spread so rapidly there has to be countless millions of spores flying round the countryside and in my area at least, they did not come from nearby potatoes as in spite of a careful search of all local potato patches none had symptoms of blight. Some may have been infected but were not advanced to spore bearing stages. My own potatoes, two rows of Deseree were growing adjacent to three rows of tomatoes. The potatoes grew on unaffected and produced perfect spuds that have lasted in store until March without any rot.

Suddenly we have tomatoes dying from blight before potatoes show any sign of infection and in fact most potatoes avoiding infection altogether. Either this is a totally new strain of blight specific to tomatoes or there is a new vector of transmission. I believe both are possibly true. There is very strong correlation between the sudden annual demise of tomatoes and the appearance of a foriegn pest Nezara viridula aka Southern Green Shield bug.

Southern Green Shield bugs on runner beans.

My well educated colleagues have all poured scorn and dirision on this theory and demand to be shown the evidence. There is none, just my obsevations. What is certain is that if the blight of tomatoes continues, we will all have to either stop growing tomatoes outdoors or find a workaround. I'm in favour of the latter.

Damage to runner beans caused by Nezara viridula.