Herbicidal Activity of IVA and IVB

As a preliminary bioassay, the inhibitory activity of cyclic 1-hydrox-yalkylphosphonates IVA and IVB against barnyard grass (Echinochloa crusgalli) and cabbage type rape Brassica napus) were tested by using Petri dish methods. The inhibitory effect of IVA and IVB against the growth of roots and stems of tested plants were examined. The results are listed in Table 5.5. 

As seen from Table 5.5, IVA-8, IVA-10, and IVA-11 displayed the best inhibitory activity ( 90 %) against the root of barnyard grass, while IVA-2, IVA-5 and IVA-8 displayed the best inhibitory activity (84-87 %) against the root of cabbage type rape at 10 mg/L. Other cyclic 1-hydroxyalkyIphosphonates showed weaker inhibitory activity at 10 mg/L. 

Only IVA-8 had 86 % inhibitory activity against the stem of barnyard grass, but weak inhibitory activity against the stem of cabbage type rape at 10 mg/L. All other cyclic 1-hydroxy alky Iphosphonates showed weaker inhibitory activity against the stem of barnyard grass and cabbage type rape at 10 mg/L. 

The ICso of IVB-1 and IVB-10 against rape and barnyard grass were further tested. 2,4-D, a commercial herbicide, was used as a positive control for this 

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