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A study was made to evaluate the effectiveness of seed treatment (4 g/kg seed) and soil application (4 g/kg soil) of Trichoderma atroviride, T. auroviride, T. hamatum, T. harzianum, T. koningii, T. longibrachiatum, T. virens, and T. viride for managing white mould caused by Sclerotinia sclerotiorum (2 g/kg soil) in pea (Pisum sativum) under pot condition. The pea cv. Vasundhara was found highly susceptible to the white mould fungus, exhibiting irregular water-soaked lesions on stems, branches and leaves. Application of Trichoderma spp. reduced the severity of mould by 27–29% and significantly enhanced the plant growth (19–22%) and yield of pea (11–16%) over control. The treatments with T. harzianum provided maximum enhancement in the plant growth (14–32%) and yield (9–13%). The root nodulation was promoted by 14–21% (T. harzianum) and 11–17% (T. virens) over control. Overall, seed treatment with Trichoderma spp. on seeds provided relatively greater control of Sclerotinia mould of pea and subsequent enhancement in the yield in comparison to soil application.

Aims To ascertain the effectiveness of Aspergillus niger, Trichoderma harzianum, Pochonia chlamydosporia, Bacillus subtilis and Pseudomonas fluorescens against rice root-knot nematode, Meloidogyne graminicola, and to optimize their application methods. Methods and results The relative effectiveness of five indigenous biocontrol agents (BCA) against M. graminicola on rice cv. PS-5 was tested initially in pot culture. The BCAs, A. niger, P. chlamydosporia and P. fluorescens proved more effective, and significantly reduced the nematode disease. It is hypothesized that success of a biocontrol module may vary with the BCA and application methods. Hence, the effectiveness of the above three BCAs as well as seven different treatment schemes were evaluated in naturally infested farmer's fields during 2 consecutive years. In nematode-infested plots without any BCA treatments, terminal galls formed on the roots, and plants suffered a 19-31% decrease in the growth and yield. The treatments with P. chlamydosporia or A. niger through root-dip (RD) plus one soil application (SA) at 15 days after planting were found to be highly effective against the nematode. Conclusions Relatively greater nematode control was achieved with RD plus two SAs (15 + 30 DAP) but statistically the effect was on par with RD + one SA at 15 DAP. These treatments significantly reduced galling (22-25%), egg mass production (21-29%) and reproduction factor (63-70%) of M. graminicola, and subsequently increased the grain yield (11-21%). Significance and impact of the study Application methods enhanced the effectiveness of BCAs against M. graminicola. The RD plus one SA at 15 DAP proved to be most effective treatment to control root-knot disease in rice. Use of multiple treatments (root dip and SA) appears cumbersome, but in view of effectiveness and limitation of chemical control in rice paddies, farmers may adopt the above module that may lead to 11-21% yield improvement.

Plant parasitic nematodes constitute an important group of pathogens and cause 7–15% yield loss to agricultural crops. The nematodes, besides causing direct damage to plants, also possess capability to synergise other pathogens leading to development of disease complex. The nematode invasion may enhance severity of fungal or bacterial diseases or may break host resistance against a disease. Fusarium-nematode disease complexes involving root-knot nematodes, Meloidogyne spp. are widely prevalent and highly damaging to vegetable and pulse crops in India as well as in other countries. The present chapter critically analyzes the information on Fusarium-nematode wilt disease complex for it occurrence and economic significance. The role of nematodes as a biopredisposing agent in promoting infection of plants by Fusarium spp. and the mechanism of development of wilt disease complexes are discussed in detail.

Nematode infestation in the forest flora has remained a neglected area of research in India. The limited information available on this aspect shows that plant nematodes pose a serious threat to forest plants. The ectoparasitic nematodes being integral component of soil fauna, are an important cause of concern for forest flora because of their unrecognizable and debilitating impact that leads to a slow tree decline and dieback. Endoparasitic nematodes, such as root-knot nematode, pine wilt nematode, flower bud and leaf gall nematode inflict specific symptoms and serious plant damage. Further, there is a potential risk of introduction of pine wilt nematode in the Himalayan region under Indian territory, through the import of coniferous wood and wood products from the nematode prone countries especially from China directly or via Nepal, Bhutan, Myanmar etc. The situation warrants immediate attention of plant pathologists and nematologists to ascertain the status of nematode infestation in forest flora in the country and to formulate specific recommendations for an immediate line of action by the government agencies. The present review through B. B. Mundkur Memorial Award lecture has offered me an opportunity to highlight the significance of nematode infestation in India forests, before a wide and relevant scientific fraternity of the country.

The environment is the key factor that influences the host-parasite relationship. Elevated CO2 levels resulting from various anthropogenic sources may directly affect the surroundings around pathogens and plants. It is hypothesized that plants may respond differently to pathogens in the environment containing an elevated concentration of CO2. To test the hypothesis an experiment was conducted to examine the effects of intermittent exposures of elevated levels of CO2viz., 400, 500 and 600 ppm (5 hr/day on alternate days) on the development of Sphaerotheca fuliginea causing powdery mildew disease on five cucurbits species using open-top chambers. The elevated levels of CO2 acted as a growth promoter and significantly enhanced the plant growth of all five cucurbit species. Inoculation with the fungus incited specific mildew symptoms on the leaves and decreased the plant growth and biomass production of the cucurbits tested except bitter gourd. The intermittent exposures with elevated levels of CO2 aggravated the disease development. As a result, severe mildew developed on all five cucurbits, including bitter gourd, which expressed tolerance to the pathogen. Fungus colonization in terms of the number of conidia/cm2 leaf surface was significantly greater on the plants exposed to 500 or 600 ppm CO2. The stomata and trichome density and stomatal pore width were increased in the leaves of CO2 exposed plants. The CO2 exposures also accelerated the photosynthesis rate, but transpiration, stomatal conductance, salicylic acid and total phenols were decreased; fungus inoculation caused the effects just reverse of CO2. Interaction between S. fuliginea and CO2 was found synergistic at 500 ppm, whereas with rest of the concentrations it was near to additive.

Surveys of major rice growing districts in the state of Uttar Pradesh in Northern India were conducted for 3 consecutive years during 2013 to 2015 under a government-funded major research project to determine the frequency of occurrence and disease incidence of the rice root-knot nematode, Meloidogyne graminicola, in rice paddy fields. More than 800 paddy fields from 88 Tehsils (divisions within a district) in 18 major rice growing districts in Uttar Pradesh were surveyed, where M. graminicola was associated with root-knot disease in rice paddy fields based on morphological and molecular characterization of juveniles and adults. The highest frequency of disease in rice fields was observed in Aligarh (44.6%), followed by Muzaffarnagar, Shahjahanpur, and Kheri Lakhimpur (29.3, 28.0, and 27.4%, respectively). Maximum disease incidence was also recorded in Aligarh (44.6%), followed by Sultanpur, Mainpuri, and Muzaffarnagar (5.7, 5.2, and 4.5, respectively). Gall index and egg mass index values (on a 0 to 10 scale) were highest in Aligarh (3.5 and 2.1, respectively), followed by Muzaffarnagar (2.6 and 2.0) and Mainpuri (2.3 and 1.8). The average soil population of M. graminicola was highest in Aligarh (3,851 ± 297 second-stage juveniles [J2]/kg of soil), followed by Muzaffarnagar (2,855 ± 602 J2/kg of soil), whereas the lowest population was recorded in Barabanki (695 ± 400 J2/kg of soil) at the time of harvesting. Relative yield losses were also determined, and the highest yield loss attributed to M. graminicola infestation was recorded in Aligarh (47%). The yield loss was linearly correlated with the soil population density of M. graminicola and disease incidence.

This is the first study that reports management of root-rot complex caused by Macrophomina phaseolina and Rhizoctonia solani concomitantly (104−6 CFU g−1 soil) in mungbean by Trichoderma spp. under field condition. Effectiveness of Trichoderma harzianum, T. hamatum, T. viride, T. polysporum and T. koningii against root-rot causing pathogens, M. phaseolina and R. solani was evaluated in vitro (dual inoculation test). The field performance of above Trichoderma spp. against root-rot disease complex caused by M. phaseolina and R. solani in mungbean was evaluated during two consecutive years. The farmyard manure colonized by T. harzianum, T. hamatum and T. viride was applied in the soil at 250 kg/ha (50 g/microplot) under field condition. The Trichoderma strains were characterized for fungicide sensitivity to distinguish from indigenous isolates, if they are present in the field soil. Mungbean cv. T44 expressed higher susceptibility to concomitant inoculations of M. phaseolina and R. solani, and exhibited significant suppression in plant growth (12–17%) and grain yield (26–30%) in two years. Treatments with Trichoderma species controlled root-rot, and improved mungbean yield, highest with T. viride, followed by T. harzianum and T. hamatum. Soil populations of M. phaseolina and R. solani decreased significantly in the plots receiving T. viride, T. harzianum or T. hamatum, whereas Trichoderma populations increased correspondingly. Soil application of T. viride or T. harzianum effectively controlled the root-rot disease complex (5–15%) and improved the grain yield of mungbean (14–19%) in diseased plots. Overall performance of T. viride was relatively better than carbendazim.

Plant diseases are one of the major limiting factors in the production of food crops and in attaining food security and food safety. Around 40–50% of the crop produce is eaten away or destroyed by pests and pathogens, and its one fourth is attributed to plant diseases. Among various groups of plant pathogens, phytonematodes cause 5–20% yield decline in food crops, which may account to a net loss of 2–7% in crop-based food. Rice, wheat, and maize are most important food crops and are frequently attacked by plant nematodes. Generally, the crop damage caused by nematodes remains hidden to farmers because of nonappearance of discernable symptoms. In addition to direct damage, nematodes aggravate the infection of soilborne pathogens or act as vector leading to development of disease complexes. To prevent yield losses and to improve crop productivity and yield quality, it is essential to make growers realize the economic significance of plant nematodes. Adequate extension programs are needed to be implemented to demonstrate and advise appropriate nematode management methods to the crop growers. With regard to food crops, especially cereals, primary emphasis may be given to some of the most important nematode genera such as Meloidogyne, Pratylenchus, Ditylenchus, and Heterodera as these nematodes are widely distributed in agricultural fields and cause tremendous damage to food crops. Common cultural practices, viz., deep plowing, flooding, fallowing during summer, removal and burning of weeds and remnants of previous crops, use of certified and disinfested planting materials, and cultivation of non-host, resistant, or tolerant crops, may substantially prevent crop losses in cereals caused by nematodes. Further, seed priming with biopesticides of Trichoderma spp. or Pseudomonas fluorescens as a general treatment may prove quite effective in growing healthy crop with considerably higher yields.

Present study was undertaken to evaluate the effectiveness of various biocontrol agents through seed treatment against root-rot of mung bean caused by Macrophomina phaseolina under pot condition. Maximum control of the disease was observed on treatment with T. viride (46.7%) and P. aeruginosa (44.4%) which improved the yield parameters by 28.6 and 25.9%; and functional nodules by 51.9–57.0% with 22.4–22.9% greater leghemoglobin content in the nodules (P