Chilling injury of sweetpotatoes does not become evident immediately after exposure to low temperatures. Non-cured roots subjected to 40 or below during transit or on the market may develop surface pits in 2 or 3 weeks. Roots stored at 50 show evidence of cold injury after 5 months in storage. Increased decay is the best indication of such injury. The most typical symptom in the Jersey group is a type of spongy breakdown and brown discoloration of the inner tissues. After the same period of storage at 50 , the Nancy Hall variety develops a dull cast, and discoloration develops usually at the stem end. Because fungi attack the weakened tissues, the condition soon appears as typical end rot. Chilled sweetpotatoes are poor keepers in storage, and losses continue during wholesale and retail handling. The consumer may make selections that are free from decay, but be unaware of the internal condition until after the roots are cooked. Hard areas, pithy breakdown, or a darkened condition of the cooked flesh indicate that sweet-potatoes were stored at temperatures that were too low.

Freshly dug sweetpotatoes that are to be marketed promptly without curing should not be subjected to temperatures below 50 . Roots that are to be stored should be promptly cured at 85 and the subsequent storage temperatures should be maintained between 55 and 60 .

TOMATOES may suffer chilling injury in the field while they are on the vine, while they are in transit, or after they reach the market. The conditions during the normal transit period from shipping point to market generally do not lead to chilling injury, but some cars arrive at the markets each year in which the fruits have been chilled. Unless the fruits are injured to the point of physiological breakdown, the symptoms of chilling injury on tomatoes are not clearly evident. As a result much confusion exists and litigation over losses occurs each year.

Tomatoes may be considered as having been chilled when their physiological processes have been so impaired that ripening does not take place when the fruits are placed at temperatures that are normally favorable for ripening. Chilling injury ordinarily cannot be detected at the tune tomatoes are removed from cars with low temperatures. The injury usually does not become apparent until the fruits have been in the ripening room 2 or 3 days. At that time tomatoes that have been seriously chilled have a dull, lifeless, pickle-like appearance and feel rubbery to the touch. The internal symptoms are a watery (but not mushy) appearance of the tissues and a slightly fermented odor.

Alternaria rot around the stem scar and as numerous small lesions over the surface of a high percentage of the tomatoes in the ripening room usually accompanies chilling injury and is an indication that the fruits have been chilled. Fruits that are less chilled show little sign of physiological injury while in the ripening room.

Tomatoes may be held at temperatures of 32 to 40 for 3 to 5 days and still ripen satisfactorily with little or no increase in decay. Tomatoes held for 6 to 8 days will ripen satisfactorily as to color, but may show an increase in decay in proportion to the length of exposure. Tomatoes are definitely weakened by holding at those low temperatures for 9 to 12 days. Ripening is unsatisfactory and decay is extensive. Tomatoes are so weakened by holding at 32 to 40 for 17 to 21 days that the entire lot usually becomes lifeless and rots without ripening. Chilling injury develops more slowly at 45 than at 32 or 40 , but tomatoes should not be held at 45 for more than 3 to 5 days.

Ordinarily the field heat in the tomatoes when loaded is such that several days are required to cool the load to desirable temperatures, even by refrigeration. Fruits near the bottom bunker of the car, however, cool rapidly and may arrive on the market with a pulp temperature of 36 to 40 if the car was moved under bunker icing. Under normal conditions, if the transit period does not exceed 6 days, the tomatoes would be at such low temperatures for only 2 to 4 days, and those conditions are not sufficient to cause chilling injury.

If, however, the transit period exceeds 10 days and the load is refrigerated, there is danger of chilling injury to the tomatoes near the bottom of the bunker. If the tomatoes have been exposed to temperatures of 40 or below in the field for a week or more before harvesting, or stored at 40 to 45 for a week before shipping, and are refrigerated in transit, or if the car is iced and left on track at the market, the fruits may be at low temperatures for a long enough time to become chilled.

Refrigerated cars that are diverted from one prospective market to another are likely to become chilled because of the longer time in transit. Chilling injury is particularly likely in shipments made when the outdoor temperatures are low. Heavy icing at that time is undesirable. Tomatoes shipped to northern markets in winter may even need heater service to protect them against chilling injury as well as freezing.

Although tomatoes can withstand low, but not freezing, temperatures for 3 to 5 days without suffering injury, it is not advisable for the fruit temperature to be lower than 50 during transit. This recommendation is made because of the uncertainty of the previous treatment of the tomatoes and also the uncertainty of how the load may be handled before the tomatoes are ripened.

LACY P. MCCOLLOCH, a plant pathologist, joined the Department of Agriculture in 1928. His investigations have dealt primarily with storage diseases of fruits and vegetables, particularly the handling, transportation, and ripening of mature green tomatoes as relating to quality and decay. He was trained at the University of Arkansas.

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