Phytoparasitica (2002) 30 (3) - Toxicity of formaldehyde to ...

Y. Ben-Yephet, Michal Reuven and Aida Zviebil (2002)
Toxicity of formaldehyde to Pythium following repeated applications
Phytoparasitica 30 (3)
The 23rd Congress of the Israeli Phytopathological Society - February 11-12, 2002
Abstract: A formulation of formaldehyde (Fordor 37) has been found to be effective in controlling peanut pod rot disease caused by two Pythium species, P. myriotylum and P. aphanidermatum. In this work the effect of repeated application of Fordor 37 on its toxicity to these two Pythium species was studied. The same sample of sandy loam soil collected from a field was used for all experiments, with a one-month interval between one experiment and the following. In the first experiment, Fordor 37 at 300 ppm controlled completely both Pythium species. In the second and third experiments a higher concentration of the chemical was necessary to control P. aphanidermatum (600 ppm) but not P. myriotylum (400 ppm). In the following experiment control of P. aphanidermatum in 'old' soil (already treated three times with Fordor 37) was compared with that in a 'new' soil sample collected from the same field. In the 'new' soil, P. aphanidermatum was 100% controlled at 300 ppm, whereas in the 'old' soil (fourth application) control of 93% was achieved at 600 ppm. In the last experiment we compared control of P. aphanidermatum in sterilized vs nonsterilized 'new' and 'old' soils. With 300 ppm Fordor, 100% control of the fungus was achieved in both sterilized and nonsterilized 'new' soil and also in the sterilized 'old' soil. In the nonsterilized 'old' soil, however, 600 ppm Fordor controlled only 56% of the fungal population. In the present work we demonstrated that repeated applications of Fordor 37 reduce its efficiency in controlling both P. myriotylum and P. aphanidermatum, due to biodegradation of Fordor 37 in the soil. Although repeated application at this frequency is not the normal practice in the field, the results indicate a problem that could occur if growers intensify the use of this chemical, following the phasing out of methyl bromide.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Pythium aphanidermatum
	Pythium myriotylum