Control of taro blight and corm rot caused by Phytophthora colocasiae homeopathic drugs.
The effect of 4 homeopathic drugs (Kali iodide (potassium iodide), Arsenicum album (arsenic oxide), Blatta orientalis (an extract of cockroach) and extract of Thuja occidentalis) on the mycelial growth, sporangial production, pectolytic and cellulolytic enzyme production and control of P. colocasiae on taro (Colocasia esculenta) was investigated. All 4 drugs inhibited mycelial growth, but the percentage inhibition varied with different drug potencies. Max. inhibition (50-90%) was obtained by Kali iodide and A. album at all 3 potencies (3, 30 and 200) and by B. orientalis and T. occidentalis at potencies of 30 and 200. The effect on sporulation also varied with potency, with max. inhibition caused by each drug at a potency of 200, and by a potency of 30 for A. album. Kali iodide resulted in the greatest decrease in pectolytic and celluloytic activity, followed by Arsenicum, Thuja and Blatta. The occurrence of disease was reduced by 45-59% compared with an untreated control when taro leaves were treated with Kali iodide or A. album (both at 200 potencies) prior to inoculation with P. colocasiae.