1913.1 PUBLIC DOCUMENT — No. 31. 71 



MALNUTRITION OR OVERFERTILIZAITON OF 

 GREENHOUSE CROPS. 



II. D. IIASKINS. 



Crops grown in grcenlionses nnder somewhat artificial con- 

 ditions are likely to snlfer from a variety of troubles. In this 

 paper data will bo ])resentcd which strongly indicate that im- 

 perfect growth and development are due in many cases to an 

 accnmnlation of soluble plant food rather than to fnngi and 

 bacteria. 



Co^^DiTiox OF Diseased Cucumber Crop. 



The pathological description of the affected crop is briefly 

 as follows : — 



The plants, which at first are usually very vigorous, turn 

 yellow prematurely and fail to develop fridt. The leaves be- 

 come more or less spotted, resembling the mosaic troubles some- 

 times seen on other plants. WTien studied with the microscope 

 no fungous disease is apparent. The trouble does not usually 

 develop until the third year after the soil has Ix^en placed in 

 the houses, and its appearance seems to depend wholly upon the 

 manner in which the soil has been prepared and managed. 



Method of 'preparing the Soil — In those eases where the 

 trouble has been experienced the third year, the preparation of 

 the soil has consisted in mixing equal amounts of pasture sod 

 and horse manure and allowing it to remain a couple of months 

 before transferring it to the houses. Upon placing the soil 

 in the houses more manure and also some lime were added, and 

 when the cucumber plants were set a trench of horse manure 

 and chopped straw was used beneath to furnish imderground 

 heat. During the growth of the crop a considerable quantity 

 of nitrate of soda and chemical fertilizer was supplied. This 

 treatment must necessarily result in a very rich soil which pro- 

 duces a heavy crop the first year. 



