Yield loss of carrot (Daucus carota) cv. Nerac caused by Meloidogyne chitwoodi and population dynamics of this nematode were studied using a range of 13 nematode densities at three seed densities (2, 4, 18 seeds pot −1 ) in a climate-controlled glasshouse. Yield and quality data were fitted to Seinhorst's yield models. Final population densities were fitted to the population dynamic models for sedentary and free-living nematodes. The tolerance limits for yield loss were 0.34, 0.62 and 0.50, while that of quality were 0.012, 0.142 and 0.813 second-stage juveniles (J2) (g dry soil) −1 at increasing seed densities, respectively. The minimum yield (m), increased with seed density: 0.25, 0.30 and 0.50; the minimum quality yield was 0.10, 0.08 and 0.15 J2 (g dry soil) −1 at increasing seed densities, respectively. Both maximum multiplication rates and maximum population densities increased with increasing seed density but were generally low. Carrot cv. Nerac can be considered a bad host for M. chitwoodi.

Alternaria species are well‐known aggressive pathogens that are widespread globally and warmer temperatures caused by climate change might increase their abundance more drastically. Early blight (EB) disease, caused mainly by Alternaria solani, and brown spot, caused by Alternaria alternata, are major concerns in potato, tomato and eggplant production. The development of EB is strongly linked to varieties, crop development stages, environmental factors, cultivation and field management. Several forecasting models for pesticide application to control EB were created in the last century and more recent scientific advances have included modern breeding technology to detect resistant genes and precision agriculture with hyperspectral sensors to pinpoint damage locations on plants. This paper presents an overview of the EB disease and provides an evaluation of recent scientific advances to control the disease. First of all, we describe the outline of this disease, encompassing biological cycles of the Alternaria genus, favorite climate and soil conditions as well as resistant plant species. Second, versatile management practices to minimize the effect of this pathogen at field level are discussed, covering their limitations and pitfalls. A better understanding of the underlying factors of this disease and the potential of novel research can contribute to implementing integrated pest management systems for an ecofriendly farming system. © 2021 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Nematode migration, feeding site formation, withdrawal of plant assimilates and activation of plant defence responses have a significant impact on plant growth and development. Plants display intraspecific variation in tolerance limits for root-feeding nematodes. Although disease tolerance has been recognised as a distinct trait in biotic interactions of mainly crops, we lack mechanistic insights. Progress is hampered by difficulties in quantification and laborious screening methods. We turned to the model plant Arabidopsis thaliana, since it offers extensive resources to study the molecular and cellular mechanisms underlying nematode-plant interactions. We established through imaging of tolerance-related parameters that green canopy area was an accessible and robust measure for assessing damage as the consequence of cyst nematode infection. Subsequently, we developed a high-throughput phenotyping platform to non-destructively measure the green canopy area growth of 960 A. thaliana plants simultaneously. We show that A. thaliana can be used to study tolerance limits of plants to cyst and root-knot nematodes. Although our results can be adequately modelled with classical tolerance limit quantifying methods, real-time monitoring allowed more accurate growth rate measurements. Based on our findings, we believe that our phenotyping platform will enable further studies into the underlying mechanisms of tolerance to below-ground biotic stress.

The fodder radish varieties Anaconda, Contra, Defender, Doublet and Terranova, known to have some partial resistance, were compared to the standard variety, Radical, to estimate their relative susceptibility (RS) for both population dynamic parameters of Meloidogyne chitwoodi and to evaluate P\ dependency. This approach must eventually lead to new screening methods for partial resistance tests. Plants were grown under controlled glasshouse conditions. Twelve densities of nematodes in five replications were used. Five plants per 7 1 pot were allowed to grow for a period of 11 weeks until their early flowering stage. Few seedlings of all the varieties at P\ = 32 and 64 J2 (g dry soil)-1 , and all seedlings exposed to the highest density, P\ = 128 J2 (g dry soil)-1 , died within a week after germination. Replanted seedlings developed into normal plants. Total yield, expressed as total fresh weight, was not affected by M. chitwoodi. A lower percentage of plants with galls was observed on partially resistant varieties as compared with Radical. For Radical, a maximum multiplication rate (a) of 0.38 and a maximum population density (M ) of 6.43 J2 (g dry soil)-1 were estimated. Radical proved to be a bad host for M. chitwoodi with all final populations lower than the P\. The parameter estimates of (M) for Anaconda, Contra, Defender, Doublet and Terranova were 0.011, 0.006, 0.027, 0.020 and 0.009 J2 (g dry soil)-1 , respectively. With Radical taken to he 100% susceptible, this resulted in RSm values of 0.17, 0.10, 0.42, 0.32 and 0.14% of these varieties, respectively, reducing high population levels of M. chitwoodi by more than 98%. There was no correlation between the rMgans and the RSm values, indicating that scoring the number of galled plants will not provide a suitable measure for partial resistance.

Current and continuing climate change in the Anthropocene epoch requires sustainable agricultural practices. Additionally, due to changing consumer preferences, organic approaches to cultivation are gaining popularity. The global market for organic grapes, grape products, and wine is growing. Biostimulant and biocontrol products are often applied in organic vineyards and can reduce the synthetic fertilizer, pesticide, and fungicide requirements of a vineyard. Plant growth promotion following application is also observed under a variety of challenging conditions associated with global warming. This paper reviews different groups of biostimulants and their effects on viticulture, including microorganisms, protein hydrolysates, humic acids, pyrogenic materials, and seaweed extracts. Of special interest are biostimulants with utility in protecting plants against the effects of climate change, including drought and heat stress. While many beneficial effects have been reported following the application of these materials, most studies lack a mechanistic explanation, and important parameters are often undefined (e.g., soil characteristics and nutrient availability). We recommend an increased study of the underlying mechanisms of these products to enable the selection of proper biostimulants, application methods, and dosage in viticulture. A detailed understanding of processes dictating beneficial effects in vineyards following application may allow for biostimulants with increased efficacy, uptake, and sustainability.

As part of developing a routine potato cultivars resistance test to Meloidogyne chitwoodi, both the effect of nematode density (Pi) and pot size on growth, tuber yield, quality and tuber infestation level were studied in glasshouse conditions. The study was carried out in four experiments using cv. Desiree as control and seven genotypes with a single resistance gene to M. chitwoodi and 1 genotype, with resistance to Globodera pallida. Plants were inoculated with ranges of Pi from 0.0625 to 256 J2 (g dry soil)−1 in log series. Haulm height, tuber yield, starch dry matter content (SDC) and tuber quality were recorded. Additionally, harvested tubers of experiment 2 were stored for 240–300 days to estimate actual tuber infestation at planting when used as seed in a subsequent season. Haulm height was positively affected with increasing Pi’s and negatively with decreasing pot size. The yield was not affected in four out of seven genotypes with resistance to M. chitwoodi; they can be considered as tolerant, having a relative minimum yield, m = 1. Three genotypes and cv. Desiree showed relative minimum yield, m< 0.8, the latter varying between 0.67 and 0.80 over experiments and pot sizes. The reduction of SDC equalled that of yield indicating that M. chitwoodi had no extra effect on starch content. Quality, expressed as tuber-knot index (TKI), used for accepting ware potatoes for processing, was below 10 for all genotypes, except for 2011M1. The TKI values of cv. Desiree and genotype MDG2 were > 20 and are not accepted for processing. The fraction of clean tubers of the resistant genotypes had significantly increased to 91% compared to < 8% for cv. Desiree and MDG2. Tuber infestation, expressed to number of juveniles per gram dry soil of cv. Desiree after storage, showed no regression with the Pi and averaged 0.35 J2 (g dry soil)−1, while all tested genotypes provided ca. 0.002 J2 (g dry soil)−1.

The population dynamics of Meloidogyne chitwoodi on eight potato genotypes was compared to the susceptible cv. Desiree in four glasshouse experiments. The initial nematode densities consisted of log series 2x, with . Seinhorst’s logistic model was fitted to the final population densities to estimate the parameters maximum multiplication rate (a), maximum population density (M) and the ratios RSa, RSM and . Average RSa and RSM of the seven resistant genotypes were smaller than 0.29%. The ratios on six resistant genotypes and cv. Desiree were the same, 1.3, indicating independence of RS. One genotype stood out with , whereby RSa < RSM. Both RS and were unaffected by pot size or experimental conditions. Screening protocols at second-stage juveniles (g dry soil)−1 in 2 or 3 kg pots were evaluated for distinctiveness between the two genotype groups. Based on the results, an optimal protocol for a routine resistance test is proposed.

SummaryThe population densities ofMeloidogyne chitwoodiin potato tubers stored at 4, 8 and 12°C after 0, 60, 120, 180 and 240 days of storage were assessed. Compared to day 0, storage temperatures of 4 and 8°C reduced population densities to 9 and 35%, respectively, after 240 days of storage, while nematode numbers in tubers stored at 12°C increased 2.5 times. The maximum hatching rate of nematodes from tubers stored at 8 and 12°C increased linearly with storage time. At 4°C it remained constant. The time required for the hatching process to reach the maximum number of second-stage juveniles (J2) decreased with increasing storage temperature. Recovered juveniles ofM. chitwoodifrom tubers after 180 and 240 days of storage at all three temperatures were still infective and able to multiply on ‘Desiree’ with estimates of the maximum multiplication rate (a) and the maximum population density (M) of 63.6 and 70.8 J2 (g dry soil)−1, respectively.