ISHS Acta Horticulturae 487: VI International Symposium on Processing Tomato & Workshop on Irrigation & Fertigation of Processing Tomato
AETIOLOGY OF LOWER STEM SWELLING IN PROCESSING TOMATO IN THE VEGAS DEL GUADIANA (EXTREMADURA, SPAIN) |
| Authors: | R. Ortiz, C. González |
| Keywords: | Herbicide, Damage, Soil Incorporation, Fertiliser, Rooting |
| Abstract:
Lower stem swelling is the name given to a disorder seen with increasing frequency in tomato planters in the tomato area of the Vegas del Guadiana (Extremadura, Spain). Symptoms include limited root growth, especially of the lateral or secondary roots, and a typical swelling of the lower part of the stem which sometimes results in stem breakage. Many plants recover, but their maturity is delayed, especially in early transplanting. This problem has increased over the last years, and leads to disruption in factory supply programming. The aetiology of this problem is uncertain, but it seems to be caused by herbicides in combination with soil and transplanting conditions. To study this non-pathogenic disease, a greenhouse trial (Dec. 1996 – Feb. 1997) and a field trial (May – Sept. 1997) were carried out, to determine the influence of the most common dinitroaniline herbicides in the area (Pendimethalin. 1.54 1 a.i./ha: and Ethalfluralin, 1 l a.i./ha). In the greenhouse trial the herbicides were applied superficially at a depth of 3 and 5 cm into the transplanting bed. In the field trial, shallow incorporation with a cultivator and deep incorporation with a disc harrow into the whole surface were used. A starter fertiliser was applied at the time of transplanting (40 Kg/ha of N in the greenhouse trial: 15 Kg/ha of 12.60.0 in the field trial). Results from both trials showed that the herbicides contributed to stem swelling and lack of rooting, mainly when they were incorporated superficially. Damage decreased with deep incorporation of the herbicides and, to some extent, when fertilisers were used. However, no significant differences were found either in the total yield, or in the proportion of red, green or overmature tomatoes, probably due to the late date of transplanting of the trial. | |
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