The disease develops rapidly at temperatures between 50 and 60 and will even continue to produce decay at the usual cold-storage temperature of 32 .

Prompt cooling of the fruit and proper temperatures during transit and storage reduce the severity of the disease. The most practical method of preventing the spread of decay from one fruit to another in boxes is the use of copper-treated wrappers.

FUSARIUM ROTS often cause considerable losses during transportation and marketing of vegetables. Many species of the fungus are common in soils suitable for growing vegetable crops. Consequently most vegetables are contaminated by Fusarium when harvested even though they may not be infected. Some of the most destructive rots that occur during transit and storage result from infections of open wounds or bruises made during harvesting, packing, or transportation. The decays caused by Fusarium generally are most important on root crops, tubers, and bulbs, but tomatoes, cucumbers, and melons are also affected.

Some of the most serious losses of stored potatoes are due to infection of the stem end of the tubers by Fusarium while they are in the soil, through wounds made during the harvesting and handling of the crop and following such diseases as late blight tuber rot. In some seasons it is not uncommon to find lo percent or more of a lot of potatoes affected with fusarium tuber rot after being in storage a few months. The decay is fairly moist and light brown at first and becomes darker brown and somewhat dry with age. When the decayed areas reach a diameter of an inch or more they usually become sunken, the skin is wrinkled, and here and there small tufts of white, pink, or yellowish mold appear. After long storage periods, some of the tubers may be almost completely rotten. Hollow places in some of them are lined with white, pink, or yellow mold.

Care in harvesting and handling to avoid injuries to the tubers and close grading at shipping time will do much to reduce loss by fusarium rot.

Serious loss of onions during transit, storage, and marketing is often due to rot caused by species of Fusarium. Infections usually occur through the root system or through injuries made during harvesting and handling.

Onions with visible decay are discarded at packing time, but those with only slight infections are difficult to grade out. They and the onions with wound infections cause much trouble in storage and transit. The decay produced by Fusarium is yellowish brown and moist at first but later becomes spongy. A white or pink mold develops in and on the larger decayed places. Badly injured onions and' those showing signs of decay should not be stored. If they are shipped they should be used immediately.

The fusarium decays of melons usually are the result of infection through the stem or bloom end, but the fungus can enter any injured spot. The decay is moist at first but later becomes spongy. Often a conspicuous growth of white or pink mold appears. As the causal organisms grow best at 75 to 80 , the practice of precooling and shipping melons under good refrigeration is effective in checking the development of the decay during transit and marketing.

Tomatoes, peppers, cucumbers, and other kinds of vegetables that grow near or on the surface of the soil often become affected by fusarium decay at places injured by tools and insects and at spots where other diseases have opened the way for invasion. The decay is usually less serious than the fusarium rots of other crops.

GRAY MOLD ROT, caused by Botrytis cinerea, is often the cause of considerable loss during transportation, storage, and marketing of many vegetables. It is particularly damaging to some crops grown in foggy, wet weather and moderate temperatures. The causal fungus produces an immense number of spores on the infected plants. The wind-borne spores that alight on the moist surface of a susceptible vegetable germinate and invade the tissues and cause the discolorations and breakdown that we call decay. Infections may also occur through wounds made during harvesting and packing. Then the injured tissue furnishes the moisture that enables the spores to germinate. Once the fungus is within the plant tissues, it cannot be completely controlled because the organism will continue to grow even at temperatures as low as 32 F.

Transit temperatures between 40 and 50 ordinarily found in refrigerated shipments of many vegetables check the development of gray mold rot briefly but do not control it. When the vegetables reach the market and are taken out of refrigeration, the decay develops rapidly.

During long storage periods, gray mold spreads by contact to other plants within the packages. On green vegetables such as artichokes, tomatoes, peppers, peas, and leafy plants, the first sign of gray mold rot is a small, greenish-tan or brown water-soaked spot with an indefinite grayish margin that merges into the healthy tissue. In green tomatoes and peppers, infection usually starts at or near the stem and the decay spreads rapidly over the shoulders and sides of the fruits. Infections may occur anywhere on them. If there is no break in the skin, large decayed areas may be produced without any evidence of surface mold, but at injuries a fine white mold is produced; it later turns grayish brown when spores are produced. The characteristic decay and the grayish-brown, granular spore masses usually serve to identify this disease.

Gray mold rot is a serious cause of losses of storage onions. The fungus is generally inconspicuous in the field, but enough spores may be produced on a few diseased plants to infect large numbers of bulbs during harvest in wet seasons if the necks are not well cured before the onions are stored. Infections of the neck of the bulbs that are not evident when the onions are stored gradually develop into a grayish-brown decay that may involve half the bulb within a month or so. Careful curing in the field or by artificial means is the best control. measure.

Gray mold rot also causes considerable damage to stored carrots, parsnips, and similar root crops. It usually affects only the topped roots in storage and is seldom encountered in fresh bunched vegetables. Spores from dead and dying plants contaminate the roots at harvest. Most of the infections occur at the crown where the tissues are injured by topping or through wounds on the sides of the roots. The decay is light brown and water-soaked at first. Later it is somewhat spongy and darker brown. Affected areas usually have a fine white surface mold, which becomes grayish brown as the spores are formed. Once infection has occurred, the decay will continue to progress in cold storage at 32 , but the rate of decay will be retarded. Root crops suspected of having gray mold infection should be inspected periodically in storage.

LATE BLIGHT of potatoes and tomatoes is serious when moist, moderately cool weather prevails for some time during the growing season. It sometimes destroys a large part of the potato and tomato crops throughout the world. In Aroostook County, Maine, where the seriousness of this disease is well understood, an average loss of about 16 percent of the potatoes in storage was reported one season, although growers spent more than a million dollars to spray potatoes to control late blight.

The causal fungus, Phytophthora infestans, seems always to be waiting for favorable weather conditions to start an epidemic. Besides being a serious field disease, it causes great loss of potatoes and tomatoes during transportation, storage, and marketing. When rain, fog, or heavy dew keeps the plants wet immediately before and during harvesting, great numbers of spores are produced on the leaves. They contaminate the potato tubers and tomato fruits.

Affected potato tubers may show brown spots of various size anywhere on their surfaces. On late potatoes the decayed areas are firm to leathery and have fairly definite margins. Even after several months of storage the decay seldom penetrates into the tubers more than one-fourth inch. The brown or chocolate-colored decay greatly reduces the marketability of the potatoes. It also opens the way for secondary infection by species of Fusarium, which often cause a complete breakdown of the affected tubers during storage. In early or southern-grown potatoes, infections of late blight produce a reddish-brown decay, which sometimes penetrates the tubers to a depth of one-half inch. That in itself causes serious losses in transit because inconspicuous lesions over, looked at packing time continue to enlarge. To make matters worse, bacterial soft rot often follows in the blight-affected tubers. The result is that a high percentage of the potatoes is a total loss by the time they reach the market.

The disease originates each season from infected tubers used for seed from volunteer plants that develop from diseased tubers left in the field, or from plants growing on cull piles that have been allowed to remain in or near the field. The amount of late blight infection can be reduced greatly by carefully disposing of the cull potatoes or by killing the sprouts from cull potatoes by burning or weed-killing chemicals.

Late blight may be satisfactorily controlled in most seasons by the use of thorough spray programs, but sometimes the weather is so favorable for development of the disease that satisfactory control cannot be obtained. When the potato plants are infected, a marked degree of control of tuber rot can be had by killing the plants with chemicals or by other means a week or two before the potatoes are harvested and stored.

In one experiment in which the potatoes were harvested and stored when part of the foliage was green and infected with late blight, there was a loss of 48 percent of the tubers in storage; potatoes harvested from the same field after the foliage had been killed developed only 4 percent of late blight tuber rot in storage.

The development of late blight tuber rot in potatoes is influenced greatly by the storage temperatures. Even when tubers are harvested from green plants that show late blight, a great reduction in storage loss may be obtained by storing the potatoes immediately after harvesting at 32 to 36 F. for about 60 days. Tubers harvested and stored immediately at 50 or above may be expected to show about three times as much decay as similar potatoes stored at 32 to 36 .

Most of the tomatoes shipped to distant markets are harvested in the mature green stage so that they will carry without excessive mechanical injury. They ripen during transit or in ripening rooms at the receiving markets. During epidemics of late blight, great numbers of spores from the tomato plants contaminate the fruit at the stem scar and at wounds made during harvesting and packing. Infections and decay that occur while the fruit is still on the plant are usually visible when the fruit is being packed, and affected tomatoes can be sorted out. Infections that occur just before or during harvesting are not visible, however. Sometimes 25 to 50 percent or more of the fruit from diseased vines is lost in transit and during marketing because of decay that results from such invisible infections.