Tomato Troubles and Onions

Tomato Troubles and Onions

by Medwyn Williams, MBE FNVS National Chairman of the NVS

This article was originally published on 4th August 2004

Tomatoes Keep You Busy

You can never leave your tomatoes for a day before you find there is always something extra that you can do to them. How often I have walked into the greenhouse to find a long side shoot growing straight upwards right behind the main stem. They had probably only been checked through for side shoots a few days previously. Feeding is always paramount with tomatoes if you are to get a top quality dish from them, and the right feed at the right time is often the key. I have heard growers say that you should never feed your tomatoes with a feed that has a high proportion of Nitrogen. I disagree with that because initially you want plenty of strong growth and shoots and nitrogen is the element to give you that.

Conversely, at this time of year, with the plants approaching their peak growth, and many of you having already stopped the leading shoot weeks ago, it's now time to have a change of diet. Now that the fruit are swelling and maturing, they still require Nitrogen but importantly they now need plenty of Potash, as much as three times the ratio of nitrogen. Next to leeks and onions, I get more phone calls regarding tomato problems than any of the other vegetables and they are predominantly to do with the following question 'I have a black leathery spot underneath some of my tomatoes, how can I cure it? The answer is that it"s not curable at that stage, it isn’t a disease as some people think but a cultural problem.

Tomato Blackspot

The black spot is probably a symptom of what happened a few weeks ago rather than what occurred a few days ago as it takes time to develop within the fruit. Tomato plants easily move most nutrients around the plants, particularly Nitrogen and Potassium; Calcium however, an essential element of tomato growing, is a different ball game. If tomatoes are not watered properly and get dry around the roots when in flower, the critical period being between 16 and 21 days after pollination or in other words after the little tomato has formed, the problem kick starts.

When the plant is left too dry it struggles to move calcium around to the fruit and will take it instead to the foliage first, leaving a lack of calcium within the fruit, hence the problem. In simplistic terms the plant is taking action to save itself and in so doing is prepared to abort the fruit. If you are experiencing this problem now, continue to water and liquid feed you plant regularly but also add a level teaspoon of Calcium Nitrate to a gallon of water and add about a pint to each plant once every 10 days or so.

I am very plesed with my plants at the moment they have grown far better under a lower density. This year I only have ten plants along one side of my greenhouse and, up to now, there is no signs of any problem with Botrytis which tends to be more problematic when the plants are grown at a higher density.

Tomatoes from Rooted Cutings

The variety that I am growing this year is from my own stock of rooted cuttings from the show winning Gold Star F1, the only way you can now grow it as the seeds are no longer being hybridised by the breeder.

The cuttings grew on really well when they were potted up, but as they were cuttings, the first truss was forming very low down on the plant. This was removed and after the plants were planted in their growing bed, a further two trusses were also removed so that the first proper truss has formed about two feet above compost level.

This means that the fruit are shapely, in this instance even on the first truss. As I intend to run the leader up canes to the ridge of the greenhouse, I shall still have plenty of trusses to get fruit from. The crop is very heavy, so heavy in fact that a double truss had bent over with the weight  and had to be supported with some string

The last time I saw this was with Shirley, at that time it proved to be a disaster as the weight of the crop tore the truss away from the main stem, a particualr inconvenience with that particular variety

Onions

I completed harvesting all my onions for the under 250 grams class (picture attached) on the 11th July and I must say that they all look very even although a few do have a slightly thicker neck than I would ideally have liked. I now have four trays of 24 onions harvesting in the roof space of my garage, with each onion sitting on about two inches of fine saw dust. The variety this time is Carlos, a relatively new high shouldered variety from my own catalogue and the bulbs often have a lovely Kelsae shape with a light brown colour. They were placed in the roof space of my garage because it’s bone dry and as the weather at the time of harvesting was very inclemental, there was less chance of Botrytis setting in on them. It’s also warmer there with plenty of air movement every time I open the garage door, they should therefore colour up quite fast.

One thing I did notice with this onion is that to get it to weigh in at just under 250 grams, it has to be harvested when it’s only 10 inches around and when I noticed a few deeper bulbs in the bed, then these were harvested at 9¾", this gives you some idea of the depth of the cultivar. Even though I have 96 bulbs to select 5 for the Nationals at Tunbridge Wells, I can tell you that when it comes time for final selection, and you are striving for near perfection, it will still be hard.

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