Crop residues from groundnut and sorghum constitute important fodder resources for dairy production and fodder trading on the Deccan Plateau in India. This paper addresses the effect of important diseases of groundnut and sorghum on pod and grain yield and crop residue yield and quality. In four genotypes of groundnut, late leaf spot (Phaeoisasariopsis personata) and rust (Puccinia arachidis) are the two major foliar diseases that together could reduce pod and haulm yield by 70% and in vitro digestibility of haulms by 22%. Two genotypes (ICGV 9202 and 92093) were highly resistant to these foliar diseases maintaining high pod and haulm yield as well as high in vitro digestibility of haulms (>62.3%) even under highest disease pressure. Important diseases in sorghum investigated were a viral disease caused by maize stripe virus (MStV) and anthracnose caused by Colletotrichum graminicola. MStV reduced grain yield by 30%, stover yield by 42% and digestible stover yield by 45%. Effects of MStV were highly genotype-dependent and grain and stover were affected in different ways in different varieties. The choice of appropriate genotype for a given farming situation will depend on trade-off scenarios for benefits from grain and stover. Similarly, anthracnose could reduce grain yield by 47% and stover yield by 23% but effects on stover quality were variable. As observed for MStV, effects of anthracnose were highly genotype-dependent and genotypes were identified that maintained high grain and stover yield under high disease pressure.

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An investigation was carried out at AICRP on cotton scheme, Chamarajanagar, Karnataka during kharif season of 2016-17 and 2017-18 to evaluate the bio-efficacy of pyriproxifen 10% EW against sucking insect pests of cotton viz., whitefly (Bemisia tabaci Genn.), aphids (Aphis gossypii Glover), thrips (Thrips tabaci Lind), and leafhopper (Amrasca bigutulla bigutulla Ishida). The study indicated that spraying of pyriproxifen 10% EW @ 200 g.a.i/ha has recorded significantly higher seed cotton yield (19.43 q/ha) with maximum per cent reduction in whiteflies (95.28%), aphids (90.04%), thrips (98.78%) and leafhoppers (94.40%), respectively. Followed by spraying pyriproxifen 10% EW at 125 g.a.i/ha. However, all the insecticide treated plots were superior in reducing the pest load as compared to un treated control.

A field experiment was conducted at AICRP on cotton, Haradanahalli, Chamarajanagara during kharif 2018 to know the population dynamics of insect pests of cotton on HB2110 cultivar. The peak incidence of aphids (64.28 aphids/3 leaves), leafhoppers (5.24 leafhoppers/3 leaves), thrips (5.51 thrips/3 leaves) and whiteflies (4.97 whiteflies/3leaves) were observed during 36, 28, 40 and 38 th SMW. Pink bollworm incidence was started during 32 SMW and attended its severity at 46 th (15 larvae/20 bolls).The correlation results of the meteorological variables with insect population revealed that aphids, thrips, whiteflies and PBW showed significant positive correlation with maximum temperature while, leafhopper showed positive non-significant correlation. However, all the above pests showed nonsignificant negative correlation with minimum temperature, evening relative humidity and rainfall except leafhopper and aphids showed significant positive correlation and non-significant negative correlation with morning relative humidity, respectively.

Statistical correlation coefficient is a measure that denotes the magnitude and direction of interrelationship between any two casually related variables. The information on the genotypic and phenotypic inter-relationship of cane yield and sugar yield with their component characters interest would be of immense help to the sugarcane breeder. The character association will also help in the selection of superior genotypes from divergent population based on more than one interrelated characters. However, correlation coefficients, sometimes, may be misleading and thus, need to be partitioned into direct and indirect effects. It is important for a breeder to know how other characters influence a particular character before selecting the parental material for crossing purposes. Path coefficient analysis provides direct and indirect effects of component characters thereby enhancing the better understanding of true relationship of the component characters with yield.