Evaluating the Antifungal Activity of Some Traditional Medicinal Plant Extracts against Alternaria solani (Tomato Early Blight Pathogen) in Ethiopia

Background: Tomato (Lycopersicon esculentum Mill.) belongs to the family Solanaceae. In Ethiopia, control of early blight is largely dependent on fungicidal application. There is a research need to identify effective botanical extracts to control Alternaria solani that cause early blight of tomato and for evaluation of plant extracts through different solvents on the target pathogen. Methods: In vitro experiment was conducted to evaluate the effectiveness of crude extracts of 16 selected medicinal plants against Alternaria solani. Thus, crude extracts were extracted from medicinal plants with different solvents (methanol, ethanol and petroleum at (25%, 50% and 100%) concentrations. The Alternaria solani was isolated from infected tomato leaves showing early blight symptoms. Evaluation of plant extracts was carried out against Alternaria solani using food poisoned technique on PDA. Result: Results showed that most of the methanolic extract plants were showed significant inhibition of the mycelial growth as compared to ethanolic and petroleum ether extracts. A higher rate of mycelial reduction was recorded by ethanol extracts of Allium sativum at all concentrations (100%) followed by methanol extracts of Allium sativum at 25%, 50%, 100% concentration (90.02%, 97.01%, 100% respectively). The effectiveness of extracts against Alternaria solani depends on use at the higher concentrations and various solvents. For crude extracts that have shown higher inhibitory effects against Alternaria solani in vitro conditions, actual chemical compounds should be identified. Furthermore, it is also important to evaluate these plants on other microbes, study to test in vivo and to assess their real potential field condition wherever early blight is an important disease of tomato.

Essential Oils as Biocontrol Agents of Early and Late Blight Diseases of Tomato under Greenhouse Conditions

Tomato production worldwide is usually restrained by various infections, among them mainly the late and early blight caused by Phytophthora infestans and Alternaria solani, respectively. Lately, there has been a growing concern over the use of synthetic fungicides on environmental and food safety, hence the need to explore other alternatives that are friendly to the user, the consumer, and the general environment. This research sought to test the potency of ginger, garlic, and Mexican marigold essential oils against the early and late blight diseases of tomato under greenhouse conditions. A synthetic fungicide (Ridomil Gold®) was used as a positive control while distilled water acted as a negative control. The extraction of essential oils was done by dry steam distillation and then mixed with tween twenty before being topped up with sterile distilled water. They were then used to spray tomato plants that had been inoculated with A. solani and P. infestans isolates under greenhouse conditions. The tomato plants were evaluated for growth, yield, and disease severity. The data obtained was subjected to ANOVA and separation of means was conducted using Student–Newman–Keul (SNK) test at 95% level of confidence. The three essential oils had a significant potency against the two diseases which is comparable to the synthetic fungicide. Marigold essential oil was also found to have a significant impact on the general growth of sprayed tomato plants. Essential oils of the three plants can be further explored as alternative products management of the two diseases.

Effect of biotherapic of Alternaria solani on the early blight of tomato-plant and the in vitro development of the fungus

Background: homeopathy is a means permitted in organic agriculture to control disease and plagues; biotherapics are a practical means for farmers to intervene on the health of plants in agro-ecological systems of production. Tomato-plants can be affected by several diseases, one of the most significant ones in Brazil is early blight, caused by fungus Alternaria solani, due to the damage it causes and its wide distribution in the country. Aims: to establish whether a biotherapic of A. solani may interfere on the in vitro development of the fungus and whether it affects the severity of early blight on tomato-plants in greenhouse. Methods: the effect of the biotherapic on the fungus was evaluated through the percentage of germinated spores under microscope and the growth of colonies in a culture medium. Treatments used were: biotherapic 26cH, 27cH, 28cH, 29cH and 30cH; sterilized distilled water; and diluted and agitated hydroalcoholic solution. The effect of the biotherapic on the development of disease was evaluated in 4 experiments in greenhouse. Plants were kept in vases and subjected to artificial inoculation of the fungus after the application of treatments. Evaluation of disease was carried out through diagrammatic scale. Results: no treatment affected the germination of spores or the development of fungus colonies in the culture medium. In the first test, treatment 26cH differed from water in Tukey’s test at 5% but did not differed from diluted and agitated hydroalcoholic solution. In the second test, treatments 27cH and 28cH showed significant difference from both water and hydroalcoholic solution with an average control of disease of 57% and 62% respectively. The other 2 tests did nor exhibit any significant effect. Conclusions: there was no direct effect of the biotherapic on the fungus, but there was an effect on the severity of the disease. Factors affecting the efficiency of the biotherapic must be better understood before it can be recommended to farmers for the management of early blight in tomato-plants.

Studies on some diseases of fruits and vegetable crops in relation to meteorological parameters

The role of different meteorological parameters controlling the incidences of some diseases on tomato, guava and fig grown at Pune and Padegaon in Maharashtra state were studied by graphical superimposition and correlation techniques. Peak infestation of rust on fig was observed in January at Padegaon whereas maximum infestation of fruit canker on guava and early blight on tomato were reported respectively from September to first week of October and September to November at Pune. Increase in maximum temperature was found to increase the infestation of both fruit canker and early blight. Decrease in afternoon relative humidity favoured the infestation of fruit canker and rust. Fall of minimum temperature and rise in bright hours of sunshine also aggravated the incidences of fruit canker and rust respectively.

Plant Disease Identification Using Shallow Convolutional Neural Network

Various plant diseases are major threats to agriculture. For timely control of different plant diseases in effective manner, automated identification of diseases are highly beneficial. So far, different techniques have been used to identify the diseases in plants. Deep learning is among the most widely used techniques in recent times due to its impressive results. In this work, we have proposed two methods namely shallow VGG with RF and shallow VGG with Xgboost to identify the diseases. The proposed model is compared with other hand-crafted and deep learning-based approaches. The experiments are carried on three different plants namely corn, potato, and tomato. The considered diseases in corns are Blight, Common rust, and Gray leaf spot, diseases in potatoes are early blight and late blight, and tomato diseases are bacterial spot, early blight, and late blight. The result shows that our implemented shallow VGG with Xgboost model outperforms different deep learning models in terms of accuracy, precision, recall, f1-score, and specificity. Shallow Visual Geometric Group (VGG) with Xgboost gives the highest accuracy rate of 94.47% in corn, 98.74% in potato, and 93.91% in the tomato dataset. The models are also tested with field images of potato, corn, and tomato. Even in field image the average accuracy obtained using shallow VGG with Xgboost are 94.22%, 97.36%, and 93.14%, respectively.

Cultural, Morphological and Biochemical Variability Studies among the Isolates of Alternaria solani, the Causal Agent of Early Blight Disease of Tomato

Present experiment was conducted at College of Horticulture, Bengaluru (KA) during year 2017–18 to study the cultural, morphological and biochemical variations among the isolates of the pathogen Alternaria solani, the causal agent of early blight disease in tomato. The results revealed variation among the isolates collected from different regions of Karnataka state, India with regard to the colony characteristics viz., colony colour, mycelial growth pattern, margin of the colony and zonations whereas the maximum mycelial growth in terms of diameter (90 mm) was observed in the isolates Bagalkot (BaBG) and Chikkamagaluru (CMH) on Czapek’s (Dox) agar medium while the least growth (36.33) was noticed in Bidar (BiHH) isolate. The isolate could grow better on Czapek’s (Dox) agar medium as among the 3 media tested Czapek’s (Dox) agar medium produced maximum growth of 80.70 mm and the least growth (63.70 mm) was noticed in V-8 juice agar. The morphological studies revealed that all the conidia of various isolates varied in length (25.07–42.90 µm), breadth (10.53–21.52 µm) and number of horizontal septa (2–7), longitudinal septa (0–4). Biochemical studies among the isolates revealed significant variation in their enzyme activities. The peroxidase activity was more in Chikamagaluru (CMH) isolate (81.80 Unit g-1 FW) least activity was found in Bidar (BiHH) isolate 11.78 Unit g-1 FW whereas the esterase activity was more Bengaluru (BYC) isolate (69.01 Unit g-1 FW) least activity was found in Bagalkot (BaBG) isolate 11.78 Unit g-1 FW. Existence of variation among the isolates of Alternaria solani evident from the results obtained.

Identification and Classification of Tomato Leaf Diseases Using Machine Learning Techniques

Tomato is cultivated in all countries of the world in fields, glasshouses etc. China, India, USA, Turkey, Egypt, Iran, Italy, Spain and Brazil are the important countries which are cultivating tomatoes. It is most commonly and widely cultivated in India. India is one of the countries in harvesting tomatoes. Tomato is a vital vegetable yield with respect to both income and food. Tomatoes are for the most part summer crops, yet it tends to improve steadily. Naturally, it contains A and C of vitamins which also acts as an antioxidant to prevent cancerous cells. Since the organic product contains novel features, the demand remains the same. A significant and unique feature with high nutrients gains the importance in tomatoes cultivation. Challenges towards the cultivation of tomato made us to plan for an automated machine to detect infection and to increase the productivity. This system automatically detects the infected parts and classify the types of disease which occur on the leaf like early blight, bacterial wilt, Leaf Spot, tomato mosaic virus, septoria leaf spot, leaf curl virus, and tomato spotted wilt disease using gradient anisotropic diffusion filter for pre-processing and then features are extracted using GLCM from the pre-processed leaf