Metalaxyl-M, phosphorous acid and potassium silicate applied as soil drenches show different chestnut seedling performance and protection against Phytophthora root rot

The application as soil drenches of three commercial products containing metalaxyl, phosphorous acid or potassium silicate, were studied a means controlling Phytophthora in chestnut (Castanea sativa Mill.) seedlings. In the metalaxyl treatment no plant deaths recorded, whereas with and silicate applications, untreated control, mortality rate was respectively 33.3, 44.4 77.8%. presence detected plants soils at end experiment which that did not eliminate pathogen, they only gave temporary protection to plant. treatments receiving acid, showed sharp drop growth compared surviving control. Soil analyses revealed high increase exchangeable acidity, reduction pH Mn levels treated acid. these treatments, elemental tissue analysis nutrient recovery by far above upper limit sufficiency range, toxicity being suspected cause for strong growth. These results indicate when applying such soil, their concentration and/or ability influence should be evaluated adequate measures adjustment undertaken. case its use can replaced phosphite salts. K-silicate show adverse effects on but provided less against than