138 MASSACHUSETTS HORTICULTURAL SOCIETY 



seems no doubt that the drop is a physiological disease and is 

 induced by an unbalanced condition of food elements in the soil. 

 This may occur in a soil that has been excessively fed or in a soil 

 that is lacking in plant food. 



Bud drop may be readily remedied by the application to the 

 soil of small quantities of muriate of potash and acid phosphate. 



Outdoor diseases of sweet peas. 



All the diseases considered under the heading of indoor diseases 

 are not confined to greenhouse sweet peas alone. Outdoor plants, 

 too, are susceptible to the same troubles. Thielavia root rot and 

 the mosaic are both equally serious on outdoor sweet peas, as they 

 are on indoor plants. It is not therefore necessary to repeat what 

 was already stated before. 



Beside the diseases already mentioned under greenhouse troubles, 

 there are three other important drawbacks to outdoor sweet peas. 

 These are: the Green Aphis, Anthracnose, and Streak. 



The Sweet Pea x\phis, Macrosiphum pisi Kalt. 



Of all the insect pests not one rivals, perhaps, in economic im- 

 portance the green aphis. This pest also attacks the garden pea, 

 the red and crimson clovers, as well as vetches. The lice are often 

 seen in clusters attacking practically all parts of the plant except 

 the roots. They derive their food by sucking the plant juices. 

 The pest is very prolific. It is estimated that each individual aphis, 

 if allowed full sway, would be the progenitor of 423,912 aphids in 

 one season. Fortunately, weather conditions as well as natural 

 enemies help to keep it in check. Cool wet seasons are not very 

 favorable to this pest. 



Lady beetles are our greatest friends, as they feed on these plant 

 lice. Unfortunately, many florists and gardeners have not as yet 

 learned this fact. Believing the lady beetles to be their enemy, 

 some florists do everything possible to destroy them. The writer 

 knows of a breeder of sweet peas, who as he said "experimented 

 for ten years to find out means of eradicating the lady beetles." 



