Exploitation of Selected Plant Based Insecticides for Field Management and Control of Aphids in Organic Cabbage Production

Large colonies of cabbage aphids are capable of stunting and or killing small plants. They are also capable of contaminating harvested crop. The use of biodegradable botanicals for pest control is now considered one of the best alternatives to synthetic pesticides; and they are known to be safer and ecological friendly. This study was conducted to evaluate the effect of three plant based extracts and their mixtures for their efficiency in the control of aphids in a cabbage field. Extracts from Azadirachta indica, Chrysanthemum cinerariifolium, Quassia amara, their mixtures and a positive and negative control were used. Two field studies were carried out at different periods (spring and late summer studies). Decline in aphid infestation was determined by recording number of infested plants per plot and the average number of aphids per plant; before and after each treatment application. All extracts and their mixtures decreased aphid population significantly (p<0.001) in both seasons. A mean pest population decline of 86.78% and 85.48% for number of aphids/plant was recorded in the spring and late summer study respectively; and an 86.00% and 85.48% decline in number of plants infested for the spring and late summer study respectively. Decline in infestation produced by all extracts was comparable to that of the synthetic insecticide used for the study. Keywords: Cabbage, Organic pest control, Bio-pesticide, Azadirachtin, Pyrethrin, Quassin, Plant extracts.

Evaluation of the potential yield and primary symptoms of Xanthomonas campestris pv. campestris infection in Asian vegetables grown in the Czech Republic

Selected cultivars of Asian brassicacean vegetables were evaluated for their yield potential and susceptibility to bacterial infection. Chinese broccoli, two cultivars of Chinese cabbage ('Dwarf milk cabbage' and improved 'Tahtsai'), and mizuna were grown in the conditions of the Czech Republic. Morphological and yield parameters for the field conditions (plant height, plant diameter, and marketable weight) were verified. In addition, genotypes were tested for resistance to black rot [Xanthomonas campestris pv. campestris (Xcc)] at the planting stage. The results show that a very promising genotype of mizuna, which yielded best (1,478 g per plant). Chinese cabbage (cultivar 'Dwarf milk cabbage') also showed high yield values (2,839 g per plant), especially when compared to the reference value for Napa cabbage. Chinese Cabbage 1 ('Dwarf milk cabbage') and mizuna also showed a low susceptibility to infection by bacterial black rot at the planting stage. Both cultivars reached Level 2 (median) of infection, which corresponds to the extent of the symptoms on 25% of the leaf surface.O

The Current Stage of Greening Vegetation in Selected Wine-Regions of South Moravian Region (Czech Republic)

Viticulture, as a large part of the agriculture sector of the South Moravian Region, represents significant erosion-prone land use in which soils face various agronomic issues, such as poor organic carbon levels, erosion, and fertility loss. Service crops providing a so-called ecosystem service can reduce erosion and runoff, regulate pests and weeds and increase soil organic matter and fertility. However, these crops may generate some disservices, such as water and nutrient competition; and thus, it is important for winegrowers to find applicable options for service crops depending on local soil, climate conditions, and the expected service. Inter-row management in the South Moravian Region varies from bare soils to grass cover to different types of cover with herbaceous (flowering) species. A total of 113 vineyard sites were evaluated during the years 2016 and 2017. This study presents the actual state of inter-row management in vineyards and comparison within six wine-growing regions. A two-year evaluation shows significant differences in prevalent greening management between regions. Bare soil in vineyards, the most erosion-prone vineyard floor management, appear from 10% (e.g., Bzenec, Valtice) to 19% (e.g., Mikulov, V. Bílovice) of vineyard area within evaluated regions. Bare soil management is mostly used in new plantations to reduce water and nutrient competition; however, the erosion and the runoff rates are generally higher on this variant compared to other types of cover crop management, especially on slopes. Although, alternate greening is the most used type occurring from 50% to 74% of vineyards area in five of the six selected regions, the type of inter-row vegetation differs considerably. While in Bzenec and Mikulov there is a higher appearance of herbaceous cover with native species in later succession stages, in Velké Bílovice and Valtice grass cover and commercial plant mixtures are more frequent. Knowledge current stage can be useful for planning new plantation or anti-erosion measures.O

Effect of Bacterial-algal Biostimulant on the Yield and Internal Quality of Lettuce (Lactuca sativa L.) Produced for Spring and Summer Crop

Plant biostimulants can enhance crop nutrition status, stress tolerance, yield and quality in an environment-friendly manner. The aim of this study was to determine the effect of algae and bacteria preparations on the yield and nutritional parameters of leaf and romaine lettuce cultivated for spring and summer crop. The application of a combined biostimulant consisting of plant growth-promoting bacteria (Bacillus licheniformis, Bacillus megatherium, Azotobacter sp., Azospirillum sp., and Herbaspirillum sp.) and freshwater algae (Chlorella vulgaris) was done by watering the lettuce every 14 days, and a determination of the fresh weight, total antioxidant capacity, and total carotenoids content were performed. The result revealed that the application of bacterial-algal preparation significantly affected the plant weight of both romaine and leaf lettuce in the spring and summer seasons. The highest increase in the weight of romaine lettuce reached 18.9% in the spring crop, while in the case of leaf lettuce, biostimulant treatment led to a 22.7% higher weight in the summer crop. Total antioxidant capacity and total carotenoids content showed increased values in the summer crop of romaine lettuce, while for the leaf lettuce there were no differences between treatments. Therefore, the positive effect of bacterial-algal treatment on lettuce yield, total antioxidant capacity and total carotenoids confirm that it could be applied for improving romaine lettuce yield quality and quantity, especially in stress, summer conditions

Dual Inoculation with Mycorrhizal and Saprotrophic Fungi Applicable in Sustainable Cultivation Improves the Yield and Nutritive Value of Onion

The aim of this paper was to test the use of dual microbial inoculation with mycorrhizal and saprotrophic fungi in onion cultivation to enhance yield while maintaining or improving the nutritional quality of onion bulbs. Treatments were two-factorial: (1) arbuscular mycorrhizal fungi (AMF): the mix corresponding to fungal part of commercial product Symbivit (Glomus etunicatum, G. microaggregatum, G. intraradices, G. claroideum, G. mosseae, and G. geosporum) (M1) or the single-fungus inoculum of G. intraradices BEG140 (M2) and (2) bark chips preinoculated with saprotrophic fungi (mix of Gymnopilus sp., Agrocybe praecox, and Marasmius androsaceus) (S). The growth response of onion was the highest for the M1 mix treatment, reaching nearly 100% increase in bulb fresh weight. The effectiveness of dual inoculation was proved by more than 50% increase. We observed a strong correlation (r = 0.83) between the growth response of onion bulbs and AM colonization. All inoculation treatments but the single-fungus one enhanced significantly the total antioxidant capacity of bulb biomass, was the highest values being found for M1, S + M1, and S + M2. We observed some induced enhancement of the contents of mineral elements in bulb tissue (Mg and K contents for the M2 and M2, S, and S + M2 treatments, resp.)

Oriental brassica vegetables – alternatives for a higher intake of health-promoting substances

Brassica vegetables are one of the most important groups of vegetables in terms of their nutritional composition. The aim of this work was to evaluate the lesser known Asian species from the family Brassicaceae cultivated in the conditions of the Czech Republic and to carry out a comparison with cabbage as a reference species. For the evaluation, two species of Chinese broccoli, two cultivars of Chinese cabbage (‘Dwarf milk cabbage’ and improved ‘Tahtsai’) and mizuna were selected. Among the properties evaluated were dry matter production, crude fiber content, vitamin C, carotenoids, TAC, flavonoids, phenols, and mineral composition (K, Na, Ca, and Mg). The highest contents of vitamin C were found in mizuna and the lowest in Chinese Cabbage 2. In comparison to the reference species, the majority of the properties of Chinese cabbage had higher values in comparison to traditional cabbage (range: 101–577%). Positive results were also found for mizuna. The worst brassica was Chinese Cabbage 2 in which the majority of the properties measured were lower in comparison to traditional cabbage

The change of bacterial spectrum after storage of X. Campestris pv. Campestris Inoculated Cabbage Heads (Brassica oleracea var. Capitata L.)

Changes in the bacterial spectrum of cabbage heads after storage under commonly used storage conditions were examined in this study. Cabbage seeds (Brassica oleracea var. capitata L.) were artificially inoculated with X. campestris pv. campestris (Xcc), a serious pathogen of cruciferous plants causing black rot. Isolation of bacterial cultures from Xcc-inoculated and non-inoculated cabbage heads were carried out in two time points-at the day of harvest and after four months of storage. According to our previous research and literature reports, the most frequent genera of bacteria were chosen for PCR testing, i.e., Bacillus cereus group, Bacillus subtilis group, Pseudomonas sp., and X. campestris pv. campestris. A few of the obtained bacterial cultures were negative for the four above-mentioned species. In those, other bacteria were identified by 16S rRNA sequencing. In both Xcc-inoculated and non-inoculated cabbage heads, changes of the bacterial spectrum over time were observed. The severity of Xcc infection of heads increased after four months of storage. Bacillus species represented the most frequently occurring bacterial genus. The presence of the Bacillus subtilis group increased significantly after storage in non-inoculated cabbage heads. The minor part of the other genera identified by sequencing in the first sampling were not detected in the stored cabbage heads. This was associated with a possible antagonistic behavior of Pseudomonas sp. and Bacillus sp.O

Reduced graphene oxide-based nanometal-composite containing copper and silver nanoparticles protect tomato and pepper against Xanthomonas euvesicatoria infection

Xanthomonas euvesicatoria (Xe) is of the genera Xanthomonas, which causes a bacterial spot disease that affects tomato and pepper plants, resulting in significant economic losses. Commonly used bactericides lead to pathogen resistance, environmental contamination and a current risk to human health. Herein, a nanocomposite consisting of Cu and Ag loaded onto reduced graphene oxide (rGO) was synthesized, characterized and tested. After confirmation of the antibacterial properties in vitro, nanocomposites at concentrations of 50 and 500 µg mL MINUS SIGN 1 were applied to protect tomato and pepper plants under controlled greenhouse conditions. The tomato and pepper plants indicated significantly lower disease severity when treated with the nanocomposite (15.6 and 16.7%, respectively) than when treated with the commercial copper-based bactericide Kocide(R) 2000. The nanocomposite was demonstrated as a high-efficiency biocide and has the potential for crop disease management with no phytotoxic effect.O