ISHS Acta Horticulturae 532: International Symposium on Chemical and Non-Chemical Soil and Substrate Disinfectation
THE USE OF DISINFECTANTS FOR CONTROLLING A SOILBORNE FOOT AND ROOT ROT DISEASE COMPLEX ON GREENHOUSE TOMATOES IN THE ROCKWOOL OPEN CULTURE SYSTEM |
| Author: | C. Slusarski |
| Keywords: | soilborne pathogens, soilless culture, chemical control, disinfestation, Phytophthora nicotianae |
| Abstract:
Three-year old rockwool slabs, heavily infested with Phytophthora nicotianae and Fusarium oxysporum f.sp. radicis-lycopersici, were treated prior to autumn crop of greenhouse tomatoes with the following disinfectants: hydrogen peroxide (1 %), peracetic acid + hydrogen peroxide + acetic acid (HP+PAA) at 0.2 % of commercial formulation and dimethylalkylbenzyl ammoniumchloride + polyhexamethylene-biguanidine hydrochloride (QAC+Chx) at 0.1 and 0.003 %. Under conditions of a high disease pressure, the best control of Phytophthora foot and root rot of tomato was obtained by preplanting treatment of reused rockwool slabs with HP+PAA and QAC+Chx disinfectants, which reduced the mortality of tomato plants from 75 % in untreated control to 8.3 and 16.7 %, respectively. HP+PAA and QAC+Chx increased the marketable yield by about 560 – 570 % over control. Also QAC+Chx applied before planting at a concentration of 0.003 % and then used at 0.002 % for drenching tomato plants at 7-day intervals throughout the growing period, provided significant suppression of Phytophthora nicotianae. The efficacy of hydrogen peroxide at a concentration of 1 % (10000 ppm) in controlling disease was significantly lower than that of other disinfectants tested, and inadequate to be accepted commercially. Although F.o. f.sp. radicis-lycopersici was recovered from about 40 % of root samples, no typical aboveground symptoms of Fusarium crown and root rot were observed. Cumulative total yield at the end of picking was significantly inversely correlated with root rot severity (r = - 0.726) and mean disease severity ratings on stems (r = -0.801). | |
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