Common pest and disease of Gourds – Aphids and Powdery Mildew

So far, we have shared our successful journeys with you. We thought now share some of the challenges and failures  one may encounter and learnings from it!

When we decided to grow gourds in our Research Centre, we were aware that gourds attract a lot of pest and disease – most of which are transmitted through air.

As expected, we are facing a lot of aphid infestation and powdery mildew disease to our gourd plants.

We have 4 gourd plants in our CG garden (3 in cocopeat and 1 in DWC). All plants in spite of monitoring and regular inspection have got aphid and powdery mildew infestation in the coco peat plantation. This is however comparatively less when compared with the same plant planted in the DWC system.

Aphids are small-bodied insects who, suck the sap from the plant, resulting in a retarded growth of the plants, and ultimately affecting the yield. You can read about aphids and its damaging levels in our previous blog.

Powdery mildew

Notice the white spots – Powdery Mildew

As the name itself indicates, white powdery patches appear on the upper surface of the leaves. There are several species of fungi that cause this disease in cucurbits family (Cucurbitaceae is a plant family which includes cucumber, squashes and pumpkin and melons), but there are two species which generally cause this disease. These are Podosphaera xanthii and Erysiphe cichoracearum

 

This disease is airborne. The fungal spores (=conodia) are spread/carried by the wind. It is difficult to control an airborne disease as we cannot restrict air movement.

Of course, to some extent, we can avoid disease establishment in a protected environment (poly house, shade nets) but we cannot avoid it completely as there will be air movement in the poly house as well. Another fact is that the management of disease in a poly house or in a shade net after the establishment of the disease is very difficult as the area is covered and air movement within the structure will ensure the fast spreading of the disease.

When will this disease occur? Favourable conditions for the disease development

Establishment/Development of any disease or pest population needs a suitable climate.

Powdery mildew occurs in the following conditions:

  • dense growth achieved in the plant,
  • high relative humidity with moderate temperature
  • shady condition (rather than in the full direct sunlight)

With the current temperature and climate fluctuations in our net house – the pests would be happy!

How to identify the disease?

Identification is very simple as the signs/symptoms are easy to find out; Though handling of the disease is relatively tough!

A visual inspection can show the presence of white powdery spots on the leaves and stems. As the disease starts progressing, spots increase in number, get enlarged, and spread to all regions of the plant.

 

In case of severe infestation, the affected leaves turn yellow, wither and die, leaving behind dry and brittle leaves. Flowers and fruits will not directly be affected by the disease. Damage effect will be seen in terms of mal-formed and sun-burned fruits as the plants lose their leaves in the early stages.

Damage extent

Severity of the disease leads to smaller and less number of fruits in plants.

Control measures

  • Remove disease infected leaves at the earliest sighting to avoid further spread. This will, however, only kill the existing infection.
  • Fungicide sprays – Spray protectant fungicides (horticultural oils such as neem oil) where it will prevent the new infections from occurring

Preventive strategies

  1. Grow plants in an area with full sunlight.
  2. Provide sufficient space for the plant growth to ensure better air circulation.

We hope our experiences will encourage you to move beyond short term challenges to beautiful lush green vine with little hanging gourds in your garden.

We still vouch for the joy of growing these gourds. There’s nothing more beautiful and enchanting than having a garden with plants growing around its ceiling and testifying to a forest environment – in an otherwise concrete jungle!

So pest or not (y)our happy journey continues!

Happy Gardening!!

Sushma completed her B. Sc. from College of Horticulture, Hiriyur and M. Sc. from College of Horticulture, Bengaluru. She is an avid gardener with expertise across soil based and soilless gardening techniques using substrates.

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