Relative Composition of Weeds and Integrated Weed Management in Mulberry Garden

Crop-weed competition is a limiting factor in the growth of mulberry plant and weed management practices had marked influence on weed density and weed dry matter production. Based on the weed survey in the farmers field and investigations compared to chemical weeding intercropping with cowpea had an increased weed control effect in mulberry plantations. The lowest density and dry matter of weeds were recorded in cowpea intercropping treatment. Reduced density and dry matter production of weeds resulted in increased production of mulberry growth and yield.


Materials and Methods
Weed survey was conducted for a period of one year (January 2005 to December 2005) in the farmers' field at eleven mulberry farms (Annur and surroundings (Coimbatore Dt.), Othaguthirai and surroundings (Erode Dt.) and were identified and grouped into grasses, sedges and broad leaved weeds.Weed density was estimated from replicated samples of one square meter.*1Corresponding author email: sunmuga152@gmail.comField experiments were conducted in the Department of Sericulture, Tamil Nadu Agricultural University, Coimbatore, in an established mulberry garden with V1 variety (two years old) in Field No. 68 The mulberry field was divided into 24 plots to accommodate eight treatments in three replications.Single plot size was 40 (8 x 5m) square meter with a spacing of 90 x 90 cm.The experiments were conducted (January 2006 to May 2006) in a Randomized Block Design (RBD) in three replications.The treatments imposed were hand weeding twice (one immediately after pruning and the second on 25th day of pruning), hand weeding and mulching (hand weeding immediately after pruning followed by mulching within a week with coir pith @ 12.5 t/ha), post emergence application of glyphosate 10 ml + 20 g Ammonium sulphate+ 2 ml soap per liter of water, post emergence application of glyphosate 10 ml + 20 g Ammonium sulphate+ 2 ml soap per liter of water and mulching with coir pith @ 12.5 t/ha, post emergence application of paraquat 6 ml + 2 ml of soap per liter of water, post emergence application of paraquat 6 ml + 2 ml of soap per liter of water and mulching with coir pith @ 12.5 t/ha, hand weeding after pruning and intercropping with cowpea and unweeded check.For the intercrop treatment, cowpea variety CO1 was sown in between mulberry rows at spacing of 30 x 15 cm.Seeds were sown at the rate of 20 kg/ ha.Three rows of intercrop were raised in between two rows of mulberry.Coir pith was applied at 12.5 t/ ha in the inter row spacing after hand weeding and herbicide application in the respective treatments.Recommended package of practice was followed for the cultivation of mulberry.
The weed density and dry weight were taken at the start of experiment and on 60th day from each plot randomly at five different places and expressed as number per square meter and gram per square meter.Five mulberry plants were labeled at random in each plot excluding the border rows for recording all growth and yield parameters. Mulberry yield parameters were recorded on 60th day of pruning.The results were subjected to analysis of variance and tested for significant difference (Panse and Sukhatme, 1978).

Weed survey
Weed survey revealed that the weed count varied from 6 to 19 per square meter with an average of 13.55.Out of this, the mean density of grasses, sedges and broad leaved weeds was 5.91(43.63%),1.91(14.10%)and 5.73 (42.29%) respectively (Table  1)

Weed flora
In the experimental site, a total of 13 species of weeds were recorded (Table 2).This comprised of three species of grassy weeds, one species of sedges and nine species of broad leaved weeds.Earlier fifty seven species of weeds belonging to 28 families including a Pteridopthyte was reported to occur in mulberry fields (Dhar et al., 1975).

Effect of treatments on weed density
Among the weeds, the grassy perennial weed Cynodon dactylon was the major weed species survived in all the plots irrespective of the treatments whereas the broad leaf weeds were effectively controlled to a nil density in most of the treatments.On 60th day of pruning the density of C. dactylon, the most troublesome to control, was significantly less in plots intercropped with cowpea after one hand weeding.In this treatment, the density of total weeds and Cynodon dactylon on 60 DAP was 3.60 and 2.00 per square meter respectively as against a density of 15.40 and 9.00 recorded in unweeded check (Table 3.).Anthony and Rene Van Acker ( 2005) also reported from their wheat experimental results that intercropping can enhance both weed suppression and crop production.The dry weight of total weeds was the lowest (1.60 g/m2) in the same treatment, hand weeding after pruning and intercropping with cowpea and the dry weight of Cynodon dactylon was also reduced to 1.00 g per square meter by this treatment.

Effect of weed density on mulberry
Comparing the different management practices to control the weeds, one hand weeding after pruning and intercropping with cowpea had significantly and positively influenced the biometric parameters like shoot length, number of branches per plant, number of leaves per branch and internodal length and yield  harvesting bring in an increased number of operations such as ploughing, weeding and irrigation to the field.

Table 1 . Relative density of weeds in the farmers' field
. Of the total number of weeds, G-grass, S-sedge, BL-broad leaved weeds, CD-Cynodon dactylon population of Cynodon dactylon alone was 5.27 which accounted for 38.89 per cent.Earlier, Kasiviswa nathan et al.(1978)reported that Cynodon dactylon and Cyperus rotundus were the most trouble some weeds infesting mulberry garden and accounted for 79 per cent of the total weed density.

Table 3 . Weed density (No./M2) and dry weight on 60 DAP as affected by the treatments.
Gong et al. (1994)enthesesare square root transformed values parameters like 100 leaf weight and leaf yield.Mulberry leaf yield increase due to intercropping with cowpea was 47 per cent more than unweeded check (Table4).LeiGong et al. (1994)reported that when intercropping is followed in mulberry plantations, activities related to intercrop planting, managing and