HYGIENIC CONDITIONS OF GLASSHOUSES 27 
crops. As a result it was found that on moderately 
heavy soils the unmulched tomato plants did not produce 
a lower yield than those mulched with stable manure, 
and preliminary experiments at Cheshunt Experimental 
Station have confirmed this. It is apparent that the 
need for mulching varies with different nurseries, and 
nurserymen will be wise to carry out experiments on 
their own soil. 
While mulching on some lands may not appreciably 
affect the yield per acre, it does bear an important 
relation to plant disease. Mulching with contaminated 
stable manure may introduce serious diseases into pre- 
_ viously healthy houses, but the use of such materials 
as spent hops, peat, or straw has a beneficial effect, by 
preventing splashing of soil on to the lower parts of the 
plant, and helps to keep the houses clean. ‘‘ Buckeye 
rot’ of the bottom trusses of tomatoes may be con- 
trolled by mulching sufficiently early to prevent the 
disease organisms from being splashed on to the trusses 
from the soil; but while early mulching will result in 
healthy bottom fruit, it must not be applied too early. 
Experiments have been performed whereby a mulch of 
straw was laid on the ground prior to planting, the straw 
having to be moved aside to allow the plants to be 
placed in position. It was found that such plants grew 
very slowly compared with those planted in the usual 
way. ‘Temperature records showed that the soil covered 
with straw was many degrees colder than that uncovered, 
and accounted for the slow growth of plants in the former. 
On removing the straw mulch for ten days the soil 
became warm and the plants grew rapidly. It is 
necessary, therefore, to allow the soil to become 
thoroughly warmed before applying the mulch. The 
kind of mulch, its condition, and rate of application 
have an important bearing upon plant diseases, for, 
apart from the introduction of disease organisms, such 
factors influence the plant’s susceptibility to disease. 
To obtain the best results mulching should be regulated 
