220 Diseases of Greenhouse Crops 



gas (ethylene) in the surrounding atmosphere. This 

 trouble has been overcome in floral establishments 

 where lighting gas was replaced by electricity. 



Malnutrition 

 Cause, overfeeding. 



Symptoms. The trouble is usually manifested on 

 the blossoms. It is brought about by the applica- 

 tion of an excess of certain chemical fertilizers. 

 Acid phosphate applied in large quantities seems to 

 produce no injury. An excess of dried blood will 

 produce blossoms which become soft and subject to 

 sunburn if sprinkled during sunshiny weather. Later, 

 such injured blossoms have their center petals 

 bunched, and only a few others opening. Later, 

 the buds fail to open, the foliage assumes a deep 

 green color with abundant glossiness and a normal 

 growth. If overfeeding is continued growth ceases. 

 Plants thus affected may, however, recover with ju- 

 dicious feeding. 



Overfeeding with potassium sulphate is decidedly 

 unfavorable. The edges of the inner petals crinkle, 

 brown spots appear, and often there is a withering 

 of the edges of the petals, while the center ones fail 

 to open, as though glued together. The unopened 

 buds swell, and the pistil is commonly seen project- 

 ing one inch beyond the bud. Moreover, there is a 

 retarded growth, the leaf tips begin to die, and the 

 whole plant resembles a rosette. 



