Phyllosticta leaf spot of tomato under open and protected cultivation in Himachal Pradesh

Tomato (Solanum lycopersicon Mill.) is an important off-season vegetable crop grown during March to October in Mid hills of Himachal Pradesh and fruits are transported to the northern plains where these are sold at premium prices. Now with the introduction of polyhouses, this crop is also grown during winters under protected cultivation conditions and fruits are available round the year. Due to the prevalence of congenial microclimate under protected cultivation conditions, the crop is severely infected with leaf spotting fungi. During 2009 and 2010 cropping season hybrid Naveen 2000 grown in polyhouse a new leaf spotting disease was noticed in the months of August-September. The spots on leaves were circular to irregular, coalescing to form bigger spots with papery centre which later detach from the leaf. On fruits light coloured spots with conspicuous dark coloured pycnida were observed at the point of their attachment with the plant. The spots on fruit later turned dark due to colonization of other saprophytic fungi. The severity of the disease ranged between 40 to 75 per cent in different polyhouses at Nauni. During 2011 the disease also observed in farmer's fields of district Solan where disease intensity at various localities ranged between 20–45 per cent. Pycnida were dark coloured, globose to subglobose, erumpent or submerged, ostiolated and measured 90 – 240 µm in diameter. The pycnidia released conidial mass forming a cirrhus. Conidia were one celled, hyaline, oval to slightly elongated in shape smooth and measured 3.0 – 6.0 X 2.0 – 3.0 µm. The pathogenicity of the fungus was also proved by artificially inoculating the tomato seedlings under laboratory conditions. Based on morphological characters the fungus was identified as Phyllosticta lycopersici Peck constituting a new record of occurrence of this disease on tomato in Himachal Pradesh.