Mehi Lal

By Mehi Lal, Saurabh Yadav, Vivek Singh and M Nagesh

Potato is an important food crop in the world as well as in India. It is being affected by different pathogens, viz. fungi, bacteria, viruses and nematodes. These pathogens may cause significant yield losses of the crop, if proper protection measures have not been applied. Among potato pathogens, Phytophthora infestans, Alternaria solani, Rhizoctonia solani and Fusarium spp. are the major pathogens in the fungal group, whereas Ralstonia solanacearum, Pectobacterium spp. and Streptomyces spp. are in the bacterial group. For management of these pathogens, various methods, that is, chemical control, biological control, resistant varieties, cultural control and physical control, are applied. Resistant varieties are the best and cheapest method for managing the diseases. However resistant varieties are break down their resistant over the years and moreover against some pathogen absolute resistant are not available. Chemical management is the second best option for managing the diseases, due to continuous and irrational use of the chemicals; pathogens have developed resistance against certain class of fungicides/bactericides. Moreover, these chemicals also assist in environmental pollution and toxicity in the produce. Bio‐agents are naturally occurring living organisms, which are found in rhizosphere, phylloplane, etc. These bio‐agents help in not only managing the diseases but also increasing the crop yield. Therefore, the use of bio‐agents for biological management of potato crops is the focused research area worldwide.

Part of the book: Plant Growth

By Mehi Lal, Sanjeev Sharma, Saurabh Yadav and Santosh Kumar

Potato (Solanum tuberosum L.) is the most important crop and Phytophthora infestans (Mont.) de Bary is the oomycete, which was responsible for infamous Irish potato famine during 1843–45 and it continues to cause worldwide devastation of the potato. Moreover, this disease is re-emerging in the forms of different genotypes and causes huge yield loss in the potato crop. The factors which are responsible for huge yield loss of potato are applied improper management strategies and pathogen behavior. Management strategies includes; forecasting, cultural, biological, varietal and chemical management. Forecasting is the better option for management of late blight, if accurately forecasted and promptly information reaches to the end users. As infected potato tubers cause the primary sources of infection in next season. The cultural practices will also helpful in reducing inoculum load and managing the disease. The host resistance is best option for management of this disease. However, due to very divers’ virulence nature of P. infestans; the resistance of the varieties is wiped out within a decade. Several fungicides including contact, systemic and translaminar have been evaluated from time to time; however, the pathogen has shown a remarkable capacity for change with respect to host genotype and fungicides. Nowadays biological control is gaining importance due to its eco-friendly in nature.

Part of the book: Potato

By Rahul R. Bakade, S. Sundaresha and Mehi Lal

Fungicides have been used for over 200 years to protect plants from damage by fungi, but today fungicidal resistance is very common among potato pathogens and it is difficult to control. The best and intensively studied example is metalaxyl resistance in Pytophthora infestans. Causes are many to get pathogen resistance against the fungicides like intensive use or misuse of it, repeated application of same fungicides, etc. Hence, it is today’s need to find out the different strategies like different cultural practices, use of bio-agents, use of green chemicals, elimination of disease source, etc. to manage this fungicidal resistance. There are also alternative ways like increasing host resistance, use of new molecules, etc. that can be adopted to reduce the risk of fungicidal resistance.

Part of the book: Pesticides