MARKET DISEASES OF FRUITS AND VEGETABLES 37 



GRAY MOLD ROT 



(Botrytis spp.) 



Although gray mold rot may occur in peas and beans from any 

 locality where the weather is foggy or wet and moderately cool 

 during the shipping season, the disease is seldom of great importance 

 on beans on the market. Peas shipped from California, Washington, 

 and Idaho sometimes show this decay ranging from 1 to 10 percent. 



The first symptoms of gray mold rot on peas are water-soaked 

 grayish-green spots % to y 2 inch in diameter. No mycelium is 

 evident on the smaller areas; but on the larger ones there is usually 

 a moderately fine white mold, and the central area has the grayish- 

 brown or smoke-colored mycelium and granular spore clusters that 

 characterize Botrytis species. 



Infection may take place throughout a temperature range from 32° 

 to 95° F. At 32° it takes about 2 weeks for lesions to become visible, 

 whereas at 72° they may be apparent within 2 days. At temperatures 

 between 53° and 63° infections may take place and visible lesions 

 develop within 4 days. 



Pea pods that show small water-soaked spots should not be packed 

 for long-distance shipment. 



(See 117.) 



MECHANICAL INJURY 



During the harvesting, grading, and packing of fresh green peas 

 it is impossible to avoid some bruising and other mechanical injury. 

 A large number of such injuries are so slight as to pass unobserved, 

 but when the injury is severe enough to cause death of groups of cells 

 and air is admitted into the tissues, the affected areas become con- 

 spicuous as white spots and blotches (pi. 11, C) . Unless the epidermis 

 is badly ruptured over the injured areas there is seldom much in- 

 fection and decay resulting from such blemishes. Bacterial soft 

 rot (p. 46) sometimes follows in bruised areas, if the peas become 

 warm in transit. 



MOSAIC 



Mosaic is an important field disease of peas, and a serious market 

 factor because of the distorted and poorly filled pods produced on 

 affected vines. As with most virus troubles, the symptoms usually 

 manifest are crinkling, mottling, and distortion of the leaves. Con- 

 siderable variation exists because of the fact that there are several 

 kinds of virus that affect peas. In some cases a leaf vein-clearing 

 is characteristic; in others the leaves are spotted, mottled, and severely 

 twisted and curled, and their food-making capacity is so reduced 

 that the plants are stunted and produce few or no marketable pods. 

 When the vines become severely infected before the pods are formed 

 the pods produced often are bodly distorted and mottled by dark- 

 green ridges and sunken yellowish-green areas (pi. 11, E). If any 

 seeds are developed they are likely to be smaller and more yellow than 

 normal. 



