Disease:Powdery Mildew

This is a very serious problem in cucurbits during the hot season.

  • Disease 5


  • The foliar symptoms are initiated as whitish grey superficial spots on the upper surface.
  • These spots enlarge forming large patches of powdery growth of the fungus.
  • When the attack becomes severe, defoliation followed by death of the plant occurs.
  • Considerable yield reduction results due to the infection. Fruits also get covered by powdery mass but this is not common.
  • The fruits remain under sized and sometimes deformed.


The disease is favoured by overcast skies, high temperature, reduced light intensity and succulent plant growth. The conidia of the fungus spread by means of wind and insects. The cleistothecia develop on crop debris and this can help in the survival of the fungus. The fungi are influenced by the age of the plant and air, humidity and temperature. Sixteen to 23 day old leaves are highly susceptible while very young leaves are almost immune.

Procedure for Observation

Randomly mark five one square meter area from the plot. From each square meter select 5 leaves at random and record the incidence of the disease.Count the leaves showing symptoms (even if a spot is present that leaf is considered as infected). Work out the average leaves showing infection.


  • Mere presence.
  • Control Measures

  • Cucurbitaceous weeds should not be allowed to grow near the cultivated fields of this vegetable.
  • All the affected plant parts have to be removed and destroyed to maintain crop hygiene.
  • Proprietary fungicides, which are specific for the management of powdery mildews, like dinocap (Karathane 48 EC 0.2%) spray can be used to manage the disease when it appears in a severe form.
  • The severely infected leaves/vines should be removed and destroyed before application of the fungicide/bio control agents.
  • Spraying with carbendazim 0.1%(Bavistin, B-Stin, Zoom,Bengard 50WP) or thiophanate methyl 0.1% (Topsin 75 WP, Cercobin 75% WP) also has been recommended for the management of this disease.