Articles
Impact of organic N on corky root in organically cultivated greenhouse tomatoes
Article number
1164_41
Pages
327 – 332
Language
English
Abstract
Corky root of tomato caused by Pyrenochaeta lycopersici, is a major soil-borne disease in Swedish organic greenhouse production where tomatoes are grown in soil-based substrate.
The corky root attacks the roots of the tomatoes and results in a suberisation of the roots reducing the plants ability to take up water and nutrients.
Currently, for most producers, corky root resistant grafted plants is a presumption for the production but apprehensions are that this will affect the taste and may result in a build-up of resistance.
Other methods for controlling the disease are urgently needed.
A way to decrease the problem is to replace the substrate but this is very expensive.
In the present study we tested the hypothesis that a proper N fertilization regime decreases disease severity.
A greenhouse study was conducted using ungrafted tomato plants which were grown in a substrate naturally infected with corky root at three levels of additions of organic N, combined with three different pH levels.
A high N addition increased the yields whereas a high pH reduced the yields.
We conclude that tomatoes can resist corky root better at low pH. The reduced tomato yield at high pH cannot be explained by a calcium deficiency due to calcium immobilization at high pH. For organic tomato growers, a substrate with a low pH and a proper N fertilization is recommended.
The corky root attacks the roots of the tomatoes and results in a suberisation of the roots reducing the plants ability to take up water and nutrients.
Currently, for most producers, corky root resistant grafted plants is a presumption for the production but apprehensions are that this will affect the taste and may result in a build-up of resistance.
Other methods for controlling the disease are urgently needed.
A way to decrease the problem is to replace the substrate but this is very expensive.
In the present study we tested the hypothesis that a proper N fertilization regime decreases disease severity.
A greenhouse study was conducted using ungrafted tomato plants which were grown in a substrate naturally infected with corky root at three levels of additions of organic N, combined with three different pH levels.
A high N addition increased the yields whereas a high pH reduced the yields.
We conclude that tomatoes can resist corky root better at low pH. The reduced tomato yield at high pH cannot be explained by a calcium deficiency due to calcium immobilization at high pH. For organic tomato growers, a substrate with a low pH and a proper N fertilization is recommended.
Authors
A. Mårtensson, H. Friberg
Keywords
Pyrenochaeta lycopersici, soil pH, soil ammonium, soil nitrate, soil-borne diseases
Online Articles (73)