62 DISEASES OF GLASSHOUSE PLANTS 
prepared for the plants. In replacing diseased individuals 
the method should be to remove the dead plant, water 
the hole with a pint of solution, replant with a healthy 
“individual, and again water with the solution. The 
compound has been successfully employed on commercial 
nurseries, and has a beneficial effect apart from killing 
the disease organisms, for the nitrogen it contains imparts 
a greater vigour to the plants. 
During an epidemic at one nursery the grower 
replanted two houses four times, and each time lost 
practically the whole of his plants. When replanting 
for the fifth time the soil was treated with “ Cheshunt 
Compound,” with the result that only four plants were 
lost out of two thousand. 
The disease may be aggravated by certain cultural 
conditions of moisture and temperature. Thus a rela- 
tively high percentage of moisture in the soil and the air 
is favourable to the disease organisms, and careful 
regulation of the watering, so as to keep the seed-boxes 
uniformly moist, combined with efficient ventilation of 
the propagating houses to dry out the surface soil, will 
help to keep the disease under control. The optimum 
temperature for growth of Ph. parasitica is about 30° C. 
(86° F.), and that of Ph. cryptogea and Rhizoctonia solant 
about 25° C. (77° F.). Below 12° C. (54° F.) the growth 
of all three species is very slow. When the disease has 
started among the plants the grower should endeavour 
to keep the temperature as low as possible without 
impairing the health of his crop. 
Diseased plants may be saved only by cutting away 
the lower diseased portion and treating the healthy tops 
as cuttings. 
93 
*“* DAMPING OFF’ OF CUCUMBER SEEDLINGS 
Two fungi mainly concerned with “damping off” 
of cucumber seedlings are Pythiwm de Baryanum Hesse 
and Colletotrichum oligochetum Cav. 
