Friday, August 28, 2009

Point Rot

Tomato point rotThis trouble, called also "blossom-end rot," and "black-rot," occurs on the green fruit at various stages of development, as shown above. It begins at the blossom end as a sunken brown spot,which gradually enlarges until the fruit is rendered worthless. The decayed spot is often covered in its later stages by a dense black fungous growth (Alternaria fasciculata (C. & E.) J. & G. syn. Macrosporium tomato Cke.), formerly thought to be the cause of the rot, but now known to be merely a saprophyte. Point-rot sometimes occurs in greenhouses, but is more common in field culture. It is one of the most destructive diseases of the tomato, but its nature is not fully worked out, and a uniformly successful treatment is unknown. It has been thought to be due to bacterial invasion, but complete demonstrations of that fact have not yet been published. The physiological conditions of the plant appear to be important. The disease is worst in dry weather and light soils, where the moisture supply is insufficient, and irrigation is beneficial in such cases. Spraying does not control point-rot so far as present evidence goes.

Monday, August 24, 2009

Tomato Plants from Cuttings

Tomato plants from cuttings may be easily grown, but such plants, when planted in the open ground, do not yield as much fruit as seedlings nor is this apt to be of so good quality; so that, in practice, seedlings only are used for outside crops. Under glass, plants from cuttings do relatively better and some growers prefer them, as they commence to fruit earlier and do not make so rank a growth.

Seedlings can be most easily started and grown, at least up to the time of pricking out, in light, well-ventilated greenhouses, and many large growers have them for this specific purpose. Houses for starting tomato plants should be so situated as to be fully exposed to the sun and not shaded in any way; be provided with heating apparatus by which a night temperature of 60 and up to one of 80° F. in the day can be maintained even in the coldest weather and darkest days likely to occur for 60 to 90 days before the plants can be safely set out in the open field; and the houses should be well glazed and ventilated.

Houses well suited for this purpose are often built of hotbed sash with no frame but a simple ridge-board and sides 1 or 2 feet high, head room being gained by a central sunken path and the sash so fastened in place that they may be easily lifted to give ventilation or entirely removed to give full exposure to sunshine, or for storing when the house is not needed. Hotbed sash 3x6 feet with side-bars projecting at the ends to facilitate fastening them in place are usually kept by dealers, who offer them at from $1.50 to $3 each, according to the quality of the material used.

A hot water heating apparatus is the best, but often[Pg 50] one can use a brick furnace or an iron heating stove, connected with a flue of sewer or drain-pipe that will answer very well and cost much less. It requires but 6 to 10 square feet of bench to start plants enough for an acre, and a house costing only from $25 to $50 will enable one to grow plants enough for 20 acres up to the stage when they can be pricked out into sash or cloth-covered cold-frames in which they can be grown on to the size best suited for setting in the field. When a grower plants less than 5 acres it is often better for him to sow his seed in flats or shallow boxes and arrange to have these cared for in some neighboring greenhouse for the 10 to 20 days before they can be pricked out.

Thursday, August 20, 2009

Downy mildew

Downy mildew (Phytopthora infestans DeBy.), the cause of the late blight of potatoes, will attack tomatoes during cool and very moist weather, which greatly favors its development. Such outbreaks sometimes occur to a limited extent in New England and serious losses are reported on the winter crop in southern California, but the disease has never been troublesome in other sections of the country, as it cannot develop in dry or hot weather. It affects the tomato as it does the potato, forming on the leaves dark, discolored spots, which spread rapidly under favorable conditions, killing the foliage in a few days. The fruit is also attacked and becomes covered with the mildew-like spore-bearing threads of the fungus. Bordeaux mixture properly applied is an efficient preventive.