ISHS Acta Horticulturae 82: Symposium on Production of Protected Crops in Peat and other Media
COLLAR ROT IN N.F.T. GROWN TOMATOES |
| Author: | G. C.S. Wilson |
| Abstract:
One of the common problems in the nutrient film technique is collar rot caused by salts passing up the propagating blocks, when these are placed in N.F.T. canals. Soluble salts, especially nitrogen and phosphate pass to the surface of the blocks and crystallise on the necks of the plants causing salt burns leading to constriction of the necks of the plant and restricting water uptake. Hollow stems result, with subsequent wilting and death of the plants. Analyses of peat blocks show clearly that phosphate is one of the main salts causing this problem and the results suggest that phosphate levels should be kept to a maximum of 50 ppm in the solution. Control of the rise of pH in the solution should be by nitric acid rather than by phosphoric acid if the phosphate levels rise. | |
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