TOMATO MILDEW CONTROL

Timaru Herald, Volume CXLV, Issue 21180, 29 October 1938, Page 15

TOMATO MILDEW CONTROL

WHITE ISLAND MINERAL PRODUCT

Used as a soil-dressing prior to planting (3001 b per acre) and with repeated surface applications after each watering or hoeing (1001 b per acre), White Island “No. 1 Product" gave promising results as a soil insecticide. No plants were lost from the ravages of insects during establishment, as against a loss of 12 per cent in untreated land. Slugs, snails, cutworms, grass-grubs, and wood - lice were all controlled. The plants made good establishment, and throughout the whole period of growth were more robust than were those where this product was not used. The favourable growth was characterised by stouter stems, larger leaves, broader and denser foliage, with an absence of crinkle at the edge, and firm and more uniform fruits. This favourable growth continued to resist Cladosporium some time after other plants were attacked. Though Cladosporium did finally develop, the crop was better all round and the season extended. In a section where the White Island product was not applied until some two weeks after planting, the plants did not show any better than the untreated until about 3ft high. From then onwards they began to show advantageously, and finally made far better plants than the untreated. ' So marked was the better development that several growers decided to make late applications general. Some improvement was no doubt due to this, but it is very evident that early applications, at least two weeks prior to planting, give best results, though continued light dressings are favourable and advantageous Many growers express their intention to continue the use of the product in future, both when the soil Is prepared and in combination with fertilizers throughout the season.

At the time of the emergence ot white-fly, houses treated were apparently free from infestation, indicating good control due to this product.

During the period of Cladosporium development it was though that the fumes liberated from the product were having a cleansing effect on the plants. In order to test this, an extra liberal surface dressing was given to a whole house, but it was found that this method of using the product does not control Cladosporium. Its chief benefit appears to be in assisting to build up a robust plant to resist the disease for a longer period, and as a soilinsect controllant.

With present-known control measures Cladosporium may be expected in the district about mid-October. Endeavour should be made to have the plants forward and hardily grown prior to this. Dry atmospheric conditions should be maintained during winter, the majority of the water required being applied prior to planting, and good ventilation also maintained. The use of White Island product prior to planting, and soil-surface dressings during the season, appear to control soil insects and result in more robust plants capable of considerable resistance. Super in excess disposes the plants to Cladosporium. Complete fertilizers are advisable when the land is prepared for planting, together with nitrogen in a' not immediately available form. Nitrogen should be freely used when the disease first appears. Top vegetation should be encouraged after stopping, so as to provide foliage to carry tire plants through the attack.

TOMATOES UNDER GLASS In some cases these are now in an advanced stage, depending on the time of starting, which again depends on the possession or otherwise of hotwater pipes. There is no doubt that a good deal of loss is caused by blights of various kinds. Very few will be prepared to admit that wrong treatment is the cause of blight, yet we have the statement in a bulletin of the International Institute of Agriculture that “there is no disease that is inherent in the tomato; all diseases that attack them are due to errors In treatment.” A few years ago there were heavy losses in glasshouses in different parts of the Dominion, and the Director of the Horticulture Division was called upon to have the trouble investigated. The result of the investigations which followed proved beyond doubt that the houses where the trouble occurred were kept in a condition of too much moisture. There has been a considerable improvement since that time, but still there is trouble. It should be understood that the tomato is a dry-weather plant. When the weather is dry and warm, with a fair but not excessive amount of soil-moisture present, there is little trouble with blights. A glasshouse offers facilities for controlling the atmosphere, but it is the easiest thing possible to induce excessively moist conditions.

The necessity for securing a good crop induces the use of a liberal amount of fertilisers, including sulphate of ammonia. This fertiliser affects only the vegetative parts of a plant; it does not act on the fruit except in so far as good fruit ought to follow good growth. It is quite proper to use it, but it should always be accompanied by sulphate of potash, which directly affects the fruit and also makes growth firmer and less liable to blight. I am also a firm believer in the advice of reliable authorities to the effect that no watering should be done in the latter part of the day. because it tends to create a moist atmosphere during the night, when the house should be as dry as possible. Such blights as can be controlled by spraying in the case of plants in the open ground can also be controlled by spraying plants under glass. Before spraying is done the house should be as dry as possible, and the operation should be carried out in the evening, leaving sufficient ventilation through the night to allow of the escape of moisture. In other countries, as well as in this, attention is being paid to soil-treatment for the control of blights. The following plan is being tried by a good many cultivators In England, and is claimed to be giving good results: When a fortnight old commence watering the plants every third day with a solution consisting of 1 oz. of sulphate of copper in 50 gallons of water. After six weeks’ treatment increase the strength to 1 oz. in 55 gallons, applied every fourth day. Use rain-water if possible. The same treatment is applied to cucumbers.