Studies on the phyllosticta leaf spot of ginger

Abstract

Laboratory and field experiments of “The studies on the Phyllosticta leaf spot of ginger” were conducted at the College of Horticulture Campus, Vellanikkara during 1979-1981.

The first visible symptom of the disease was observed as chlorotic specks. Fructification was more during the later stages of crop growth.

The detailed study on the plant and environmental factors influencing the disease development in the field revealed that the average number of leaves per plant has a significant positive correlation with the disease intensity.

Koch’s postulate and morphological studies proved that the pathogen causing the disease is Phyllosticta zingiberi Ramakr.

Uninjured leaves and first three leaves, even after injury, failed to exhibit the symptoms on inoculation.

Conidia germinated by putting forth single or double germtubes. Sucrose solution (1,000 ppm) supported faster and maximum spore germination and the bipolar germination noted was maximum in this solution.

The fungus entered the leaf by direct penetration of epidermal cells without appressoria formation.

The pycnidiospores and mycelia of the pathogen were found to survive even after seven months in soil under different depths and moisture conditions.

The type Maran was found to be the least susceptible followed by Karakkal and Bajpai, whereas type Vengara was the most susceptible one.

Out of the 12 fungicides tried, one per cent Bordeaux mixture and 2,000 ppm Bayer 5072 gave cent per cent inhibition of the fungal growth in both solid and liquid media. Antracol 2,000 ppm and panolil above 500 ppm in solid medium; bavistin 2,000 ppm and cuman above 500 ppm in liquid medium gave cent per cent inhibition of fungal growth.

In the field trial cuman, was found to be the most effective fungicide in controlling the disease, followed by Bordeaux mixture and panolil.

Maximum rhizome yield was noticed in cuman treated plots followed by Bordeaux mixture.