Effect of salt on seed germination and plant growth of Anacardium occidentale

In Cameroon, despite the increased growing of cashew in recent years, orchard yields remain low due to the quality of seed and unsuitable peasant farming practices. This work realized in the nursery at Wakwa aimed at evaluating the effect of different concentrations of salt on cashew germination and growth. The trial was conducted during the rainy season. The substrate was made up of a mixture of sand, black soil and cow manure respectively at 1/4, 1/2 and 1/4. Seeds were soaked in different proportions of salt solution (5%, 10% and 15%) for 24 hours. The experimental design was a complete randomized block comprising four treatments, each of which was replicated three times. Treatments consisted of different percentage of salt (5%. 10% and 15%) and the control without salt (0%). Salt concentration acted in different ways on germination, survey rate and plants growth. Germination inhibition by salt changed according to the salt concentration and time, being highest at the start of experiment and decrease over time. At 28DAS, 5% and 10% concentrations did not have an inhibitory effect, which made it possible to improve survey rate at this time. Conversely, 15% had a stimulating effect on the vigor and plants growth of cashew. This study showed that soaking cashew seeds in the salt after 24 hours at different concentration does not delay germination and concentration 15% allow to obtained well growth and more vigorous plants.

Evaluation of Fungicides and Bioagents against Fusarium proliferatum under In vitro by Spore Germination Inhibition Technique

Background: Bottle gourd is a cucurbitaceous vegetable of culinary and medicinal importance cultivated in various tropical and sub-tropical regions of world. This crop is exposed to a wide variety of seed and soil mycoflora, out of which Fusarium proliferatum is utmost important as far as seed germination, viability and seedling vigour are concerned. Methods: Study was taken up to evaluate different fungicides and bioagents for their efficacy against the fungus Fusarium proliferatum under in vitro through spore germination inhibition technique. Result: Spore germination inhibition of 86.00%, 85.00% and 81.33% was recorded with hexaconazole (5% SC) @ 0.2% (C3), mancozeb (75% WP) @ 0.3% (C3) and Pseudomonas fluorescens (1% WP) @ 2% (C3), respectively. The inhibition in spore germination by mancozeb (75% WP) and Pseudomonas fluorescens (1% WP) was upto 77.33% and it was 61.78% and 67.33% in treatments involving carbendazim (50% WP) and Trichoderma harzianum (1% WP) that could be exploited to devise integrated approach for disease management.

Screening of Existing and New Boxwood Cultivars for Disease Resistance and In Vitro Fungicide Screening to Manage Boxwood Dieback Caused by Colletotrichum theobromicola

Boxwood is one of the most common and widely planted perennial ornamentals in both home gardens and commercial landscapes. Recently reported boxwood dieback, a fungal disease caused by Colletotrichum theobromicola, has been spreading at an alarming rate within the U.S. Boxwood breeders, nursery growers, and landscape professionals have shown great concerns regarding the lack of effective management practices. Therefore, the primary objectives of this study were to devise effective disease management strategies including screening cultivars to determine their susceptibility to boxwood dieback and screening various fungicides to determine their effectiveness in managing the disease. Host range studies were conducted by screening a wide variety of boxwood cultivars under greenhouse conditions. Although, boxwood cultivar ‘Little Missy’ showed much delayed symptom expression as compared to rest of the cultivars but none of the 11 cultivars were found to be resistance to boxwood dieback. In vitro screening of nine fungicides was conducted to determine mycelial growth as well as spore germination inhibition of eight isolates of C. theobromicola collected from eight states in the U.S. Of the nine fungicides, difenoconazole+pydiflumetofen showed maximum mycelial growth and spore germination inhibition at 1 ppm active ingredient followed by fluxapyroxad+pyraclostrobin, and pyraclostrobin+boscalid at 5 ppm active ingredient. Azoxystrobin+benzovindiflupyr significantly inhibited mycelial growth at 1 ppm but reduced spore germination at 10 ppm active ingredient. This study provides the boxwood industry professionals with critical and applied information pertaining to host susceptibility and fungicide efficacy to effectively mitigate boxwood dieback and to reduce its further spread.

Biological activity of Pyraclostrobin against Coniella granati causing pomegranate crown rot

Pomegranate crown rot caused by Coniellagranati is one of the most severe diseases of pomegranate. To date, no fungicides have been registered for controlling this disease in China. Pyraclostrobin, belonging to strobilurin fungicides, has a broad spectrum of activity against many phytopathogens. In this study, based on the mycelial growth and conidial germination inhibition methods, we investigated the biological activity of pyraclostrobin against C. granati at the presence of 50 μg/mL SHAM using 80 isolates collected from different orchards in China during 2012-2018. The EC50 (50% effective concentration) values ranged from 0.040-0.613 μg/mL for mycelial growth and 0.013-0.110 μg/mL for conidium germination, respectively. Treated with pyraclostrobin, the hyphae morphology changed and conidial production of C. granati decreased significantly. The result of transmission electron microscope showed that treatment of pyraclostrobin could make the cell wall thinner, and lead to ruptured cell membrane and formation of intracellular organelle autophagosomes. The pyraclostrobin showed good protective and curative activities against C. granati on detached pomegranate fruits. In field trials, pyraclostrobin showed excellent control efficacy against this disease in which the treatment of 25% pyraclostrobin EC 1000× provided 92.25% and 92.58% control efficacy in 2019 and 2020, respectively, significantly higher than that of other treatments. Therefore, pyraclostrobin could be a candidate fungicide for the control of pomegranate crown rot.

Discovery of succinate dehydrogenase candidate fungicides via lead optimization for effective resistance management of Fusarium oxysporum f. sp. capsici

Fusarium wilt of chili caused by the fungus Fusarium oxysporum f. sp. capsici (FCO) severely reduces the production of chili worldwide. There is growing evidence of resistance to commercial fungicides targeting succinate dehydrogenase (Sdh) of FCO soliciting the development of new Sdh inhibitors (SdhIs). In the current work, optimize docking and virtual screening were used to mine twelve SdhIs from the ZINC database, followed by in vitro antifungal evaluation on spore and radial mycelium development. Four new promising SdhIs exhibiting a mean mycelium inhibition rate greater than 85.6% (F = 155.8, P = 0.001, P < 0.05) were observed on ten strains of virulent resistant FCO. Importantly, three of the discovered molecules exhibited potent spore germination inhibition (≥ 80%, P = 00.1, P < 0.05) compared to the commonly used fungicide penthiopyrad. A significant positive correlation (r* ≥ 0.67, P < 0.05) between the activities of the newly discovered SdhIs compared to penthiopyrad against all tested FCO strains indicated a broad-spectrum fungicidal activity. The current findings indicate that the four SdhI’s discovered could judiciously replace certain commercial SdhIs displaying resistance against F. oxysporum f. sp. capsici.

Formulation, Characterization and Evaluation of Encapsulated Bioherbicide on Echinochloa cruss galli and Phalaris minor

Weeds management under organic agriculture demands organic herbicides / bioherbicides.to address this issue an experiment was conducted in Centre of Environment Sciences and Technology, Central University of Punjab, Bathinda to study the effects of different concentration and bioassay of encapsulated essential oil extracted (EOs) from Callistemon viminalis on Echinochloa cruss galli and Phalaris minor under lab conditions. Encapsulation efficiency of gum arabic and maltodextrin (GAMD) EOs increased from 26 to 31% for 4 to 8% of EOs concentration. The sizes of all the particles were found in the range of 1-10 μm. The reduced size in case of EOs loaded GAMD-EOs encapsulates may be due to the application of spray drying method used during the preparation. Maximum germination inhibition was observed with P. minor as compared to the E. crus-galli L. The probable reason behind this may be the relatively smooth seed coat, smaller weight to volume ratio of P. minor as compared to the E. crus-galli L. Among all the treatments basal application of encapsulates with 8 % essential oil was found more lethal and result in maximum phyto-toxicity by registering less shoot length and root length and fresh biomass weight. Also, the individual constituents of the EOs can be explored for their use as herbicides and then their encapsulated formulations can be used for scale up in the field conditions.

Potential of two cover crops, signal grass and ruzi grass: suggested allelopathic effect on some important weeds

There is evidence that signal (SG) and ruzi (RG) grass have an allelopathic effect on weeds. This study aim to evaluate this effects on difficult-to-control weeds: hairy beggarticks (HB), benghal dayflower (BD), horseweed (H), sourgrass (S) and tall windmill grass (TWG). The first experiment was installed in a completely randomized design with 2 donor species (SG and RG) × 4 extract concentrations (0, 75, 150 and 225 mg ml−1) in factorial scheme with four replicates. Weed germination percentage was evaluated in three-day intervals. In the second experiment, the weeds emerged in substrates previously cultivated with SG and RG, in completely randomised block design with four replicates. The emergence, shoot growth and root growth were evaluated. The results were as follows: (i) on horseweed (H), 84% germination inhibition by RG leaf extracts and 38% emergence inhibition by SG root exudates were observed; (ii) on benghal dayflower (BD), 84% germination inhibition by RG leaf extracts and 37% emergence inhibition and 4.3 times the SRL values than control by RG root exudates; (iii) on hairy beggarticks (HB) 52% germination inhibition by RG leaf extracts scored, while SG root exudates reduced 43% of the emergence, 24% shoots biomass accumulation and 11.3% root length; (iv) on sourgrass (S) 71% germination inhibition by both donor plants and 75% germination inhibition by RG leaf extracts were measured. Finally, on tall windmill grass (TWG) 69% germination inhibition was observed upon using both donor plants. It can be concluded that foliar allelochemicals inhibit the germination of: BD > S > TWG > H > HB, while root exudate allelochemicals, inhibit the emergence and root development of all weeds

Mycoflora impact on germination and vigour of bottle gourd (Lagenaria siceraria) seeds and its management through different plant protectants

Bottle gourd is an important cucurbitaceous crop. The impact of 14 species from eight fungal genera on bottle gourd seeds was studied through in vitro tests. Bottle gourd seeds were inoculated with each isolate separately and subjected to various germination tests. Maximum germination inhibition was upto 69.3% due to Fusarium proliferatum. Inoculation of seeds with F. proliferatum significantly reduced the germination speed index to 2.69. The seedling vigour index I for seeds inoculated with F. proliferatum and F. incarnation-equiseti (species complex) was 860 and 861, respectively, significantly different from that of non-inoculated seeds having a vigour index of 1791. The seedling vigour index II of seeds inoculated with F. proliferatum was 1818, significantly lower than the control (4631), indicating that the F. proliferatum isolate was highly virulent among all the isolates. Amongst seven plant protectants evaluated for their efficacy as seed dressers against F. proliferatum, propioconazole (25% EC), copper oxychloride (50% WP) and Mancozeb (75% WP) were effective in reducing infection. Germination percentage was highest for seeds treated with the bioagent Trichoderma harzianum 1% WP.