Root-knot nematodes (RKN) are globally distributed and highly pathogenic. By determining the threshold at which damage occurs, we can create effective measures to protect plants from nematodes. In our study, we investigated the impact of ten initial population densities (Pi-log series) of M. javanica, i.e., 0, 2.38, 2.68, 2.98, 3.28, 3.58, 3.88, 4.18, 4.48 and 4.78 juveniles (J2) g(-1) soil on tomato cv. S22 plants in pots. The graphical estimation of yield losses caused by RKN was calculated using Seinhorst's yield loss model based on the relationship between the RKN population and damage to tomato plants. The relationship between initial nematode population density (Pi) and plant yield was analyzed using Seinhorst's model, where T is the tolerance limit, m is the minimum yield, and z is a constant describing yield decline. This allowed us to determine the threshold at which nematode infestation significantly reduces tomato growth. Seinhorst's model, y = m + (1-m) 0.95(Pi/T-1) for Pi > T; y = 1 for Pi <= T for RKN, was fitted to the data of shoot length and fresh weight of infected and uninoculated control plants to estimate the damage threshold level. The impact of M. javanica on plant physiological parameters, including chlorophyll content, carotenoid and nitrate reductase activity, root-gall formation, and disease incidence, was also determined in this study. The tolerance limits for relative tomato shoot length and fresh weight were 3.34 J2 of M. javanica g(-1) soil. The minimum relative values (y(m)) for shoot length and fresh weights were 0.39 and 0.42, respectively. We found that the damage threshold level was between 3.28 and 3.58. The root galls index, nematode population and reproduction factors were 3.75, 113 and 29.42, respectively, at an initial population density (Pi) of 3.58 J2 g(-1) soil. The chlorophyll (0.43 mg g(-1)), carotenoids (0.06 mg g(-1)) and nitrate reductase activity (0.21 mu mol min(-1) g(-1)). Our study highlights the importance of the accurate estimation of damage thresholds, which can guide timely and effective nematode management strategies.

Spent mushroom substrate (SMS), a waste product from mushroom cultivation, in addition to being rich in essential nutrients for crop growth, contains actively growing mushroom mycelia and metabolites that suppress some plant pathogens and pests. SMS thus has potential for fostering the suppressiveness of soil-borne pathogens of farms. This study determined the potential of using the spent Pleurotus ostreatus substrate (SPoS) to suppress the plant-parasitic nematode Radopholus similis in bananas. R. similis is the most economically important nematode in bananas worldwide. The effect of SPoS on R. similis was assessed through two in vivo (potted plants) experiments between May 2023 and June 2024. Five-month-old East African highland banana (genome AAA) plantlets that are highly susceptible to R. similis were used. In the first experiment, the plantlets were established in 3 L pots containing (i) pre-sterilized soil, (ii) pre-sterilized soil inoculated with nematodes, (iii) pre-sterilized soil mixed with 30% (v/v) SPoS, (iv) pre-sterilized soil mixed with 30% (v/v) SPoS followed by nematode inoculation, (v) SPoS without soil, and (vi) SPoS without soil inoculated with nematodes. The SPoS was already decomposed; thus, it may or may not have contained active mycelia. The nematodes were introduced two weeks after the SPoS application. In the second experiment, SPoS was introduced two weeks after nematode inoculation. The SPoS treatments without soil were not evaluated in the second experiment. Both experiments were monitored over a three-month period. Each screenhouse treatment contained four plants and was replicated thrice. In the first experiment, data were collected on changes in soil nutrient content, below- and aboveground biomass, root deaths, root necrosis due to nematode damage, and R. similis population in root tissues and soil. In the second experiment, data were collected on root deaths and the number of nematodes in root tissues and the soil. The SPoS improved crop biomass yield, reduced root damage, and colonization by R. similis. The potential of SPoS to improve the management of R. similis and banana production under field conditions needs to be determined.

Compost tea is widely recognized for its beneficial effects on crop growth and soil health. However, its efficacy varies depending on the composition of the feedstock and brewing conditions. This study investigates the chemical composition and agronomic impact of compost tea prepared from a commercial mixture of plant residues and animal manure. Standard chemical analyses, combined with solid-state 13C CPMAS NMR spectroscopy, were employed to characterize the organic chemistry of the feedstock. High-throughput sequencing of bacterial and eukaryotic rRNA gene markers was used to profile the microbiota. Compost tea was applied to three crops, Allium cepa, Beta vulgaris, and Lactuca sativa, grown in protected Mediterranean environments on volcanic soils. The 13C CPMAS NMR analysis revealed that the feedstock is predominantly composed of plant-derived tissues, including grass straw, nitrogen-fixing hay, and animal manure, with a significant presence of O-alkyl-C and di-O-alkyl-C regions typical of sugars and polysaccharides. Additionally, the chemical profile indicated the presence of an aliphatic fraction (alkyl-C), characteristic of lipids such as waxes and cutins. The compost tea microbiome was dominated by Pseudomonadota, with Pseudomonas, Massilia, and Sphingomonas being the most prevalent genera. Compost tea application resulted in significant yield increases, ranging from +21% for lettuce to +58% for onion and +110% for chard. Furthermore, compost tea application reduced slug damage and enhanced the shelf life of lettuce. These findings highlight the bio-stimulant potential of this standardized compost tea mixture across different vegetable crops.

Pioneering results of seed-potato health improvement and the suppression of soil-borne infection during the potato production by the preplant coating of tubers with an azoxystrobin-loaded degradable polymer film coating are presented. The film coating was applied to the surface of potato tubers by spraying with a 1% solution of the degradable polymer poly(3-hydroxybutyrate) in dichloromethane mixed with azoxystrobin. The film coating did not damage the tubers or reduce germination. The half-life of the polymer coating in field soil was 25 days. The film degraded gradually from potato planting to the beginning of flowering, ensuring long-term delivery of the fungicide to the plants. In the experimental group, a more effective reduction in the total number of rhizospheric soil fungi, including plant pathogens Alternaria alternata and Fusarium oxysporum, was revealed, compared with the preplant treatment of tubers with the commercial fungicide azoxystrobin (comparison group). The healing effect of the fungicide-loaded coating led to an improvement in the quality of the potato crop. In the experimental group, the total yield and the share of marketable tubers exceeded those of the comparison group by 5.6 t/ha and 8%, respectively. The proportion of Fusarium infected tubers was 8.5% in the experimental group versus 12.1% in the comparison group. The fungicidal effect of a long-term degradable polymer film coating with azoxystrobin was more successful than traditional treatment of tubers with a solution of this fungicide. Thus, the proposed approach is promising for the protection of seed potatoes.

Paramyrothecium comprises saprobic and plant pathogenic members. Eight plant-pathogenic Paramyrothecium species have been recorded in Asia, America, and some parts of Africa and Europe. Among the commonly reported species are P. roridum and P. foliicola. Several Paramyrothecium species are associated with coffee leaf spots, muskmelon crown rot, and eggplant crater rot. Paramyrothecium is commonly found in soil, decaying plant material, and diseased fruits, stems, and leaves of several plant species. The life cycle of Paramyrothecium species includes an asexual stage throughout disease development, with no sexual morphs reported. Environmental factors, such as temperature and humidity, influence the distribution and prevalence of Paramyrothecium. Paramyrothecium-associated diseases occur through various mechanisms, including wind and rain dispersal of conidia, contaminated soil, and plant debris. Paramyrothecium disease development can be exacerbated when the soil is wet and plant tissues are damaged, which served as pathogen entry. Adequate water management, soil sanitation, and proper handling of crops are important to minimize losses in commercial crop production. Several biological control agents and pesticides have also been reported to control the pathogen and the associated disease.