Field Studies on the Effect of Rye Cover Crop on Soybean Root Disease and Productivity

Cover crops improve soil and water quality in annual cropping systems, but knowledge of their impact on soybean (Glycine max L.) seedling and root diseases is limited. The effects of winter rye cover crops (Secale cereale L.) on soybean population, biomass, root morphology, seedling and root diseases, pathogen incidence, canopy reflectance, and yield were assessed over two years in Iowa and Missouri, USA. Plots without a rye cover crop were compared to plots with early-kill rye and late-kill rye cover crops, which were terminated 34 to 49 days or 5 to 17 days before soybean planting, respectively. Soybean shoot dry weight, root rot severity, and incidence of Fusarium spp. and Pythium spp. on roots were not influenced by the treatments. Soybean grain yield and plant population were reduced in the presence of rye in two site-years, increased in one site-year, and not changed in the remaining site-years. Soybean canopy reflectance was measured at 810 nm and measurements were first made at 70 to 80 days after planting (DAP). At least five measurements were obtained at 7- to 15- day intervals, ending at 120 to 125 DAP. Measurements at approximately 120 to 125 DAP differed by treatments but were not consistently associated with the presence or absence of a rye cover crop. Our field studies suggest that Iowa and Missouri soybean farmers can use winter rye as a cover crop in soybean fields with low seedling disease pressure without increasing the risk of seedling and root diseases or suppressing yield.

The Use of Fermented Typha Domingensis Residues by Pleurotus Ostreatus as A bio-Fortification to Control Root Disease on Cucumber Caused by Rhizoctonia Solani

Cucumber is one of important crops and susceptible to root disease caused by Rhizoctonia solani. The study aimed to evaluate the efficiency of two isolates of P. ostreatus (Ah and Ak) and soil treatment with several rates of Typha domingensis residues fermented by P. ostreatus to control R. solani that causes root diseases on cucumbers. In vitro trails, R. solani inhibited significantly by isolate (Ah) as well as redial mycelial growth and the percentage of cucumber seeds germination. In field trails, the number of germinated seedlings was highest at fermented T. domingensis 59.81 compare to control treatment which was 59.81. Disease severity (DS) of root damage was recorded in R. solani and R. solani + Fermented T. domingensis treatments and reached 70.4 and 64.27 respectively.

Soil Mixtures As An Element That Increases The Immunity Of Meadow Bluegrass To The Causative Agent Of Root Diseases Of Fusarium Etiology

The article considers the possibilities of using compiled soil samples in the cultivation of meadow Bluegrass with the compilation of load indicators in the form of root diseases of fusarium etiology. The considered preference for this culture is due to the component part of the lawn mixture, where, according to its characteristics, it plays an important role in the formation of a stable landscape composition in the form of a “podpushka”.

Soil Biodiversity and Root Pathogens in Agroecosystems

Soil ecosystem is a living and dynamic environment, habitat of thousands of microbial species, animal organisms and plant roots, integrated all of them in the food webs, and performing vital functions like organic matter decomposition and nutrient cycling; soil is also where plant roots productivity represent the main and first trophic level (producers), the beginning of the soil food web and of thousands of biological interactions. Agroecosystems are modified ecosystems by man in which plant, animal and microorganisms biodiversity has been altered, and sometimes decreased to a minimum number of species. Plant diseases, including root diseases caused by soil-borne plant pathogens are important threats to crop yield and they causes relevant economic losses. Soil-borne plant pathogens and the diseases they produce can cause huge losses and even social and environmental changes, for instance the Irish famine caused by Phytophthora infestans (1845–1853), or the harmful ecological alterations in the jarrah forests of Western Australia affected by Phytophthora cinnamomi in the last 100 years. How can a root pathogen species increase its populations densities at epidemic levels? In wild ecosystems usually we expect the soil biodiversity (microbiome, nematodes, mycorrhiza, protozoa, worms, etc.) through the trophic webs and different interactions between soil species, are going to regulate each other and the pathogens populations, avoiding disease outbreaks. In agroecosystems where plant diseases and epidemics are frequent and destructive, soil-borne plant pathogens has been managed applying different strategies: chemical, cultural, biological agents and others; however so far, there is not enough knowledge about how important is soil biodiversity, mainly microbiome diversity and soil food webs structure and function in the management of root pathogens, in root and plant health, in healthy food production, and maybe more relevant in the conservation of soil as a natural resource and derived from it, the ecosystem services important for life in our planet.

Population dynamics, effective soil factors, and LAMP detection systems for Phytophthora species associated with kiwifruit diseases in China

China has the largest area of kiwifruit production in the world. Pathogens associated with root diseases of kiwi trees have not been investigated extensively. In this research, three Phytophthora species including P. cactorum, P. cinnamomi, and P. lateralis, which are pathogenic to kiwi trees in the main planting areas of China, were studied. The population densities of these species in 128 soil samples from 32 kiwi orchards in 2017 and 2018 were measured using multiplex real-time quantitative PCR, based on the ras-related protein gene Ypt1. P. cactorum was the most widely distributed of the three species in orchards of the Zhouzhi and Meixian Prefectures. We also used redundancy analysis (RDA) to examine soil factors in the kiwi orchards, to understand their effects on the population densities of the Phytophthora species. The RDA analysis indicated that soil temperature and pH were significantly correlated with the abundance of P. cactorum and P. cinnamomi. Besides, two loop-mediated isothermal amplification (LAMP) detection systems for P. cactorum were developed based on the tigA gene. The color-change detection system was proved to be accurate, sensitive, and faster than quantitative PCR. The results of this study, along with the LAMP detection systems, will be of great use in the control of Phytophthora diseases for the production of kiwifruits in China.

INFLUENCE OF WEATHER PARAMETERS ON THE INCIDENCE OF ROOT ROT (MACROPHOMINA PHASEOLINA) DISEASE IN MULBERRY

Root rot disease caused by M. is the major disease in mulberry. The study was conducted in 50 mulberry gardens covering 15 villages during the year 2012-13 by adopting random sampling method. The present survey was taken up in the viz., Coimbatore, Erode, , , , and to assess the incidence of root diseases. The environmental factors that most seriously affect the initiation and development of infectious plant disease are temperature and humidity of the air, amount of rainfall, soil temperature, moisture and fertility. These factors affect disease development through their influence on the growth and susceptibility of the host, on the multiplication and activity of the pathogen or on the interaction of host and pathogen relates to the severity of symptom development. Correlation studies have revealed that average temperature plays the key role in disease incidence invariably in all the locations studied except district, which had no correlation with any of the weather variables, studied. root rot incidence attained peak during a particular period of a month where weather parameters like Temperature, Relative Humidity, Rainfall, Soil Moisture, and Soil Temperature were favorable. The root rot incidence will be minimum if all these conditions are unfavorable. Seasonal analysis revealed that South West Monsoon season was the predominant season for root rot incidence in mulberry. All the locations had peak incidence during SWM season only. The least occurrence had no specific season as it occurs in all the remaining three seasons.

Resistance to Charcoal Rot Identified Within Soybean Cyst Nematode Resistant Accessions

Two infectious root diseases that cause significant yield losses worldwide in soybean [Glycine max (L.) Merr.] are charcoal rot caused by Macrophomina phaseolina (Tassi) Goid. and the soybean cyst nematode, caused by Heterodera glycines Ichinohe. The objective of this research was to evaluate resistance to charcoal rot in a set of 120 soybean accessions reported to have resistance to one or more races of soybean cyst nematode so that lines with combined resistance could be identified. These accessions were screened in infested field in 2006 and 2007. Charcoal rot severity ranged from 1 to 5, where 1 is resistant and 5 susceptible. The result showed that out of the 120 soybean accessions tested for charcoal rot resistance 12 were identified to have moderate levels of resistance, 51 had moderate susceptibility, and 60 were susceptible. Furthermore, the accessions with moderate resistance to charcoal rot had resistance for one to two races of soybean cyst nematode. Within the lines identified with moderate resistance to charcoal rot, nine had a yellow seed coat, a desirable agronomic trait. These lines can be used as parents in soybean breeding programs for developing soybean cultivars with combined resistance to both charcoal rot and soybean cyst nematode.

The Effect of Foliar Fertilization with Micronutrients on Disease Severity and Mycotoxin Concentrations in the Grain of Winter Spelt (Triticum Aestivum spp. Spelta L.): A Case Study

The effect of mineral fertilization (NPK), foliar fertilization with micronutrients (Cu, Zn and Mn) and the NanoGro biostimulant on the severity of leaf, spike, stem base and root diseases in winter spelt cv. Schwabenkorn was evaluated in a field-plot experiment. A mycological analysis was performed and the content of Fusarium mycotoxins in grain was determined. Mineral fertilization (NPK), foliar fertilization with micronutrients and the NanoGro biostimulant exerted varied effects on the severity of Septoria leaf blotch and Septoria glume blotch, they promoted the spread of brown rust (excluding the NPK + NanoGro treatment) and inhibited the spread of black head mold (excluding the NPK treatment), eyespot and Fusarium foot and root rot (excluding the NPK + Mn treatment). Fertilization had no influence on grain yield or the content of Fusarium mycotoxins in grain. The concentrations of deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEA) and fumonisins FB1 + FB2 did not exceed the maximum permissible levels (except for DON in NPK + Cu + Zn + Mn and NPK + NanoGro treatments). Throughout the experiment, ergosterol (ERG) concentrations were highest in the grain of unfertilized spelt plants.