Diagnosis and Management of Certain Important Fungal Diseases of Citrus

Abstract

Citrus is susceptible to a number of fungal pathogens causing incalculable losses to the crop. Occurrence of a particular pathogen, its ability to cause disease, survival and subsequent spread to cross threshold level in order to damage the crop are governed by agro-climatic conditions, varietal susceptibility, soil type etc. Among fungal diseases, the soil borne diseases of Citrus are widespread whereas other foliar diseases are climate dependent. Once the soil-borne pathogen enters in a given locality, in presence of susceptible hosts and favourable environmental conditions for its growth and multiplication, it becomes the endemic problem of the area. Once the soil-borne pathogen is established, it is difficult to eradicate. The chemical treatments to control the pathogen become a recurring costly affair and environment concern. Regular use of chemical in control of soil-borne pathogens may also lead in development of resistance. Among the soil borne pathogens, the diseases caused by Phytophthora species are wide spread in all the citrus growing belts of the world and cause incalculable losses. Dry root rot caused by Fusarium species is also a serious problem in certain countries. To manage the soil borne pathogens, it is essential to raise or select disease free plant material. Wherever possible quarantine and sanitary measures should be followed to avoid introduction of disease. Good drainage and aeration of soil should be maintained for healthy and adequate growth of root system. Resistant and compatible rootstock should always be used considering the diseases prevalent in the locality. Correct diagnosis and regular monitoring of the diseases are required for their quick and economically feasible management. The use of fungicides in control of Citrus diseases is justified only if significant losses are anticipated and no other cultural options left to manage the disease. For foliar diseases, weather monitoring and its record in relation to disease eruption in earlier seasons will be helpful in developing strategies in control of the diseases. Predisposing factors for disease development which can be averted with cultural operations should be minimized or eliminated to control the diseases.