34 MISC. PUBLICATION 4 40, U. S. DEPARTMENT OF AGRICULTURE 



Peas 



The common garden pea (Phum sativum L.), a member of the 

 pulse family, is grown extensively for its edible seeds. Usually the 

 pods are not eaten, but in a few varieties the pods are sometimes 

 used for food. Regardless of kind or variety, the marketability of 

 peas depends chiefly upon the pods being fresh, green, well filled, 

 and free from blemishes and decay, as well as upon the tenderness 

 and flavor of the seeds. There are many diseases and growing con- 

 ditions that have direct and indirect effects upon the market qualities 

 of peas. 



The seedling diseases (damping-off), produced by Pythium spp., 

 RMzoctonia sp., and Selerotima sclerotiorum (Lib.) DBy. (see Cel- 

 ery, Watery Soft Kot, p. 56), either kill the plants outright or so 

 reduce their vitality that both the quantity and quality of marketable 

 peas are seriously affected. Similar effects are produced by other 

 fungi which cause root rots and wilt 7 (Fnsarium spp. and Aphano- 

 myces euteiches Drechsler). Of the diseases which directly affect 

 both the vines and the pods, the most important are bacterial spot 

 and pod spot. Several diseases like anthracnose, downy mildew, sep- 

 toria leaf spot (Septoria pisi West.), and powdery mildew cause no 

 great loss unless seasonal conditions happen to be especially favor- 

 able for the growth of the organisms. Mosaic frequently affects the 

 foliage so severely that fruit -pod production is greatly diminished, 

 and sometimes the pods are seriously distorted. On the market, bac- 

 terial soft rot (p. 46), gray mold rot (p. 37), rhizopus rot. and watery 

 soft rot (p. 56) are the most serious diseases. Scab and mosaic are 

 sometimes serious market defects. 



Blemishes caused by insects such as thrips and the serpentine leaf 

 miner {Agromyza pusiUa Meig.) are occasionally serious marketing 

 factors. 



(See 66, 83, 96, 101, 109. 110, 111, 112. 120. lol, 158.) 



ANTHRACNOSE 



(CoUetotrirJutm pisi Pat.) 



In general, anthracnose of pea appears so similar to pod spot that 

 probably the two diseases often have been confused. During a few 

 seasons the disease has been serious in some localities in Wisconsin. It 

 is quite evident that under suitable conditions it has possibilities of 

 producing great damage in some pea-growing sections of the United 

 States, if the fungus once becomes established. It affects the plants 

 in the field, lowering their productivity, and also spots the pods so that 

 they become unsightly and are unfit for marketing. 



There is one report of the appearance of this disease on the market. 

 Although it is possible that some spotted pods have been passed as 

 pod spot, it seems probable that anthracnose will not be of market 

 importance until the disease becomes more widely distributed. 



All aerial parts of the plants are affected. On the leaves, small irreg- 

 ular spots are formed with light-brown centers and grayish-brown 



» LinfokDj Maurice B. pka diseases in the united states tn 1928. D. S. Bur. riant 

 Indus., riant Dis. Bptr. Su|>. 67: 1-14. 1929. [Mimeographed!] (See p. 10.) 



