Control of phanerogamic parasites infesting mango

Abstract

To study the intensity of infestation of Loranthus and to suggest its control measures in mango orchard, survey and field experiments were conducted during 1992 – 93. The survey was carried out in three D.A.F. viz., Peringamala, Anchal, Mavelikkara and Instructional Farm, attached to the College of Agriculture, Vellayani. It was revealed from the survey that the Loranthus species Helicanthes elastic was attacking the mango orchards in all the locations of southern Kerala. It was also noticed that the rate of infestation of the parasitic weed was greater in older orchards than in younger ones. Out of the eight common varieties cultivated in all the locations, Bangalora variety recorded relatively lesser infestation than others. The field experiments were confined to Instructional Farm College of Agriculture, Vellayani. The experiment pertaining to the cultural control measures had three treatments viz., clearing of the parasite once in three months (T1) clearing of the parasite once in six months (T2) and unweeded control (T3), with six replications tested in a Randomized Block Design. Frequent lopping of the parasite as administrated in T1 recorded the least number of the infestations, biomass and carbohydrate uptake compared to T2. The number of haustoria spread of infestation, nutrient uptake and protein uptake were found to be comparable between T1 and T2. T2 was found to be more economical than T1. The chemical control experiments comprised of four herbicides viz., Simazine 10 mg a.i per litre (C1), atrazine 10 mg a.i per litre (C2), glyphosate 10 mg a.i per litre (C3) and dalapon 10 mg a.i per litre (C4) with two methods of application viz., padding and infusion with three replication in a Randomized Block Design. Infusion of all the herbicides invariably recorded its superiority in controlling the parasite than by padding. Among the four herbicides tried atrazine and glyphosate appreciably controlled the number of infestations, spread of infestation and biomass of the parasite. The uptake of nutrient, carbohydrate and protein by the parasite was also reduced by the application of atrazine and glyphosate. Infusion of atrazine and glyphosate was found to be the best treatment in controlling parasite growth and development. No visual symptoms of toxicity was found on the host after the application of any of the herbicides. Residual content of atrazine in the mango fruits was found to be below the toxicity level.