15 



Rots. 



For blossom end rot of tomatoes (bacterial, Fusarium, etc.), give 

 the plants pl.enty of water when the fruit is forming. Keep the 

 atmosphere of the house fairly moist, although not enough so to induce 

 scab. In general a house should not be kept too moist during the 

 night, as infection is likely to result. The foliage of greenhouse 

 plants should be watered only on bright, sunshiny mornings, when it 

 will dry ofif quickly. For chrysanthemum stem rot prevent over- 

 crowding and give sufificient light and air. For carnation dry rot 

 (Fusarium), select healthy cuttings and avoid planting in infected 

 soil, extreme forcing and adverse conditions in general. Outdoor 

 culture seems to be more favorable for dry rot than greenhouse cul- 

 ture. For lettuce rot (Sclerotinia) and Rhizoctonia of lettuce, 

 radishes, and carnations (wet rot), and timber rot of tomatoes and 

 cucumbers (Sclerotinia) sterilize the soil. 



Rusts. 



For chrysanthemum rust select healthy stock and pick off all 

 rusted leaves. In outdoor culture avoid exposure to dews and exces- 

 sive moisture on the foliage. Carnation rust is best avoidedjby 

 selecting rust-free stock and avoiding excessive moisture on the 

 foliage during periods when there is no sunshine. The application 

 of lime to the foliage and sub-irrigation have proved successful in 

 checking the rust. 



Burns, Wilts, Etc. 



For lettuce top-burn maintain low temperatures on cloudy and 

 succeeding days. The principal feature in lettuce growing is main- 

 taining low night temperatures, when the plants are making their 

 most rapid growth, and avoiding too high day temperatures. The 

 night temperature for lettuce may range from 35° to 45°, depending 

 upon conditions. On cloudy days it should not exceed 65°, but dur- 

 ing periods of bright sunshine, the temperature may run higher in 

 the daytime. 



Extreme cases of cucumber wilt are caused by insufficient light, 

 too high temperatures and lack of air. Leaf burns are often brought 

 about by an excess of certain chemical constituents in the soil. To 

 prevent leaf curl, stem curl, contorted leaves and various other mal- 

 formations occasionally seen in greenhouses, avoid too concentrated 



