Genetic diversity and potential inoculum sources of Fusarium species causing cankers in bareroot-propagated almond trees in California nurseries

Previous research determined that Fusarium acuminatum and Fusarium avenaceum are important causal agents of a canker disease in bareroot-propagated fruit and nut trees in California that emerges during cold-storage or after transplanting. The disease largely disappeared after 2001, but it reemerged in 2011 in almond trees in at least one nursery. This motivated further study of the etiology and epidemiology of the disease by undertaking studies to determine distribution of the pathogens throughout almond nursery propagation systems and trace possible sources of inoculum. Research initiated in 2013 detected pathogenic Fusarium spp. throughout the almond propagation system, including in healthy trees, in soils, on wheat rotation crops, on equipment, and in the cold storage facility air. In addition to the two Fusarium spp. implicated previously, Fusarium brachygibbosum and a new Fusarium species, Fusarium californicum, were found to be pathogenic on almond trees. Multi-locus sequence typing and somatic compatibility testing confirmed that isolates within a species collected from different materials in the nursery were all highly genetically similar and likely of one clonal lineage. These findings affirm that equipment surfaces, wheat rotation crops, soil, cold storage facility air, and asymptomatic almond tree materials (i.e., rootstock cuttings, budwood, and scions) can potentially contribute inoculum to increase disease prevalence and severity.

Use of Crop Rotations, Cover Crops and Green Manures for Disease Suppression in Potato Cropping Systems

Crop rotations and the inclusion of cover crops and green manures are primary tools in the sustainable management of soil-borne diseases in crop production systems. Crop rotations can reduce soil-borne disease through three general mechanisms: (1) serving as a break in the host-pathogen cycle; (2) by altering the soil physical, chemical, or biological characteristics to stimulate microbial activity and diversity; or (3) directly inhibiting pathogens through the release of suppressive or toxic compounds or the enhancement of specific antagonists. Brassicas, sudangrass, and related plant types are disease-suppressive crops well-known for their biofumigation potential but also have other effects on soil microbiology that are important in disease suppression. The efficacy of rotations for reducing soil-borne diseases is dependent on several factors, including crop type, rotation length, rotation sequence, and use of the crop (as full-season rotation, cover crop, or green manure). Years of field research with Brassica and non-Brassica rotation crops in potato cropping systems in Maine have documented the efficacy of Brassica green manures for the reduction of multiple soil-borne diseases. However, they have also indicated that these crops can provide disease control even when not incorporated as green manures and that other non-biofumigant crops (such as barley, ryegrass, and buckwheat) can also be effective in disease suppression. In general, all crops provided better disease control when used as green manure vs. as a cover crop, but the addition of a cover crop can improve control provided by most rotation crops. In long-term cropping system trials, rotations incorporating multiple soil health management practices, such as longer rotations, disease-suppressive rotation crops, cover crops, and green manures, and/or organic amendments have resulted in greater yield and microbial activity and fewer disease problems than standard rotations. These results indicate that improved cropping systems may enhance productivity, sustainability, and economic viability.

​The Impact of Growing Legume Plants under Conditions of Biologization and Soil Cultivation on Chernozem Fertility and Productivity of Rotation Crops

Background: The combined use of green manure and legumes in binary legume-crop mixtures allows farmers to efficiently produce a sufficient amount of human food and animal feed. The purpose of this study is examine how biologization and the use of different soil cultivation techniques in legume cropping affects chernozem soil fertility and productivity of rotation crops. Methods: The studies were conducted between 2017 and 2019 in 3 crop rotations. The first (control) crop rotation comprised of a clean fallow phase, winter wheat, barley and sunflower. The second crop rotation was that of green-manure fallow (clover), winter wheat, barley, sunflower and clover with oilseed radish as green manure. The third crop rotation included alfalfa, winter wheat combined with alfalfa, followed by barley, followed by sunflower and alfalfa with oilseed radish as green manure. Result: The three-year data indicated that there was an improvement in the physical properties of soil. The water resistance of soil aggregates increased by 9.7 per cent. There was a steady tendency towards an increase in detritus content (1.5 times), the amount of soil aggregates (one-third) and water resistance of the soil aggregates (9 per cent).

Diseases of Fodder Crop Rotation Crops Depending on their Cultivation Technologies

Заболеваемость растений является одной из основных причин снижения их продуктивности. В интенсивных технологиях проблему фитосанитарного состояния решают за счёт обработки посевов пестицидами, однако технологии, основанные на этом, ведут к загрязнению земель и водных ресурсов, деградации почвы в результате антропогенных процессов, негативному влиянию на здоровье человека. Альтернативой таким технологиям являются экологические и органические способы ведения сельскохозяйственного производства, однако при этом отмечается снижение продуктивности выращиваемых культур. Поэтому требуется всесторонняя оценка эффективности различных технологий. Для решения этой задачи с точки зрения распространения и развития болезней культур кормового севооборота были проведены научные исследования в совместном опыте кафедры «Агрономия» ФГБОУ ВО Ярославская ГСХА и Ярославского НИИЖК – филиала ФНЦ «ВИК им. В. Р. Вильямса» на дерново-подзолистой среднесуглинистой почве в 2020 году с использованием общепринятых методик. В результате изучения пяти технологий выращивания однолетних и многолетних трав, яровой тритикале, ячменя и кукурузы было установлено, что использование экологических технологий, особенно органической, не способствовало ухудшению фитосанитарного потенциала, а зачастую приводило к его улучшению в посевах вико-овсяной смеси, кукурузы, многолетних трав первого и второго лет пользования. Применение интенсивных технологий положительно сказалось на снижении заболеваемости ячменя и многолетних трав 3 года пользования. При этом урожайность достигала своего максимума на технологиях, обеспечивающих высокий агрофон (интенсивных технологиях), за счёт высоких норм удобрений и применения пестицидов. Таким образом, снижение продуктивности кормовых культур при использовании органической и биологизированной технологий, по сравнению с интенсивными, не было связано с ухудшением фитосанитарного состояния их посевов. The incidence of plants is one of the main reasons for the decrease in their productivity. In intensive technologies, the problem of phytosanitary state is solved by treating sowings with pesticides, but technologies based on this lead to pollution of land and water resources, soil degradation as a result of anthropogenic processes, and a negative impact on human health. An alternative to such technologies is ecological and organic methods of agricultural production, but at the same time, there is a decrease in the productivity of crops grown. Therefore, a comprehensive assessment of the effectiveness of various technologies is required. To solve this problem from the point of view of distribution and development of diseases of fodder crop rotation crops, scientific researches in joint experience of the Agronomy department of the FSBEI of Higher Education Yaroslavl SAA and the Yaroslavl RIFP – branch FSBSI Federal Williams Research Center of Forage Production and Agroecology on the soddy podzolic middle loamy soils in 2020 with use of the common methods were conducted. As a result of the research of five technologies for growing annual and perennial grasses, spring triticale, barley and corn, it was found that the use of environmental technologies, especially organic, did not contribute to the deterioration of phytosanitary potential, but often led to its improvement in sowings of the vetch and oat mixture, corn, perennial grasses of the first and second years of use. The use of intensive technologies has positively affected the decrease in the incidence of barley and perennial grasses for 3 years of use. At the same time, yield reached maximum on technologies that provide high agrophone (intensive technologies), due to high fertilizer rates and the use of pesticides. Thus, a decrease in the productivity of fodder crops using organic and biological technologies, compared with intensive ones, was not associated with a deterioration in the phytosanitary state of their sowings.

Productivity of a cereal-row crop rotation in the context of an applied biologization practice

The research was carried out to study the effect of biological preparations (Gribofit and Imunazot), applied both separately and together with nitrogen fertilizers (at the rate of 10 kg of NPPN. per 1 ton of straw) with the use of by-products as fertilizer on crop yield and productivity of the link of the cereal-row crop rotation “sunflower–barley-soybean”. The work was carried out in 2018-2020 in Kursk Region on typical slightly eroded heavy-loamy chernozem. The results are obtained for the following variants: 1. crushed by-products of crop rotation crops (control); 2. crushed by-products of crop rotation crops + nitrogen fertilizers at the rate of 10 kg of NPPN per 1 ton of cereal straw; 3. crushed by-products of crop rotation crops + biological preparations (Gribofit and Imunazot); 4. crushed by-products of crop rotation crops + biological preparations (Gribofit and Imunazot) + nitrogen fertilizers at the rate of 10 kg of NPPN per 1 ton of cereal straw. The results of the studies showed that the application of biological preparations against the background of surface embedded crop by-products provided an increase in the yield of all the crops of the crop rotation link in relation to the control. But higher efficiency was noted when using nitrogen fertilizers against the background of the applied crushed plant residues, it was 10.67 thousand grain units per 1ha, which exceeded the control by 3.19 thousand grain units per 1 ha (42.6%).

Effects of Crop Rotation and Biocontrol Amendments on Rhizoctonia Disease of Potato and Soil Microbial Communities

Rotation crops and biocontrol amendments were investigated for suppression of Rhizoctonia solani on potato (Solanum tuberosum) and their interactive effects on soil microbial communities. Greenhouse trials were conducted to evaluate selected rotation crops, including barley, common and “Lemtal” ryegrass, clover, potato, and combinations of barley with ryegrass or clover, for their effects on populations of R. solani and Rhizoctonia disease. Potato and clover preceding potato resulted in higher disease severity than most other rotations, whereas ryegrass reduced stem canker severity. In addition, all ryegrass treatments resulted in substantially higher populations of R. zeae. Field trials evaluating selected biocontrol treatments in combination with different rotations were conducted at two locations in Maine. Potatoes were treated with the biocontrol organisms Laetisaria arvalis, Trichoderma virens, or Bacillus subtilis and planted following rotation crops of barley and ryegrass, barley and clover, or potato. The barley/ryegrass rotation significantly reduced incidence and severity of stem canker and increased tuber yield at one location. Efficacy of the biocontrol treatments varied by rotation and location, with L. arvalis and T. virens reducing black scurf in some rotations and increasing some aspects of tuber yield at one location. Soil microbial community characteristics differed among rotation crops and biocontrol treatments. Significant crop by biocontrol interactions were observed demonstrating the complex interactions among rotation crops, biocontrol treatments, and soil microbial communities, as well as indicating that biocontrol can be enhanced within beneficial rotations.

Productivity of crop rotation using fertilizers and herbicides in the Vologda Oblast

The work shows that in the Vologda region on sod-podzolic medium loamy soil, the use of various doses of fertilizers significantly increased the productivity of rotation crops both with and without herbicides. Fertilizer doses calculated by the balance method for the planned yield using the balance coefficients of nutrient utilization from fertilizers and soil increased the removal of nitrogen, phosphorus, potassium, both by crops and weeds, compared to the control.

Effects of Shoot Size and Genotype on Energy Properties of Poplar Biomass in Short Rotation Crops

Eight poplar genotypes grown in a short rotation forest plantation established in an acid soil in South Europe were sampled at the age of 7 years to determine the energy properties regarding thermochemical conversion. The goal was to address the effect of selection of genotypes or shoot size at harvest on the energy quality of biomass. Between 34 and 50 biomass samples were obtained for each genotype: three disks were systematically sampled along the stem and were pooled together with a subsample of leafless branches representative of the biomass share of this component. Several energy properties were determined: higher calorific value, net calorific value, fresh moisture content, basic density, ash, volatile matter, fixed carbon content and elemental composition. Genotype had a significant effect on most of these properties, and the balsam genotypes displayed superior quality parameters and also higher biomass yield than the Euramerican genotypes. As a covariate, shoot basal diameter had a significant effect on the moisture content, basic density, ash content and on the concentrations of the elements N, K, Ca, Mg, S, Na and C. It was concluded that genotypes with low nutrient requirements planted at low density (<8000 cuttings ha−1) and harvested at a long enough rotation (7 years) produce good yields and high chip quality. Poplar short rotation crops can be grown to produce chips of A2 quality for non-industrial heating use (according to UNE-EN ISO 17225-4), able to be combusted in domestic thermal facilities of <1 MWth power.