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Cucurbits

Cucurbits – an overview:

This page provides an overview of the key pests and diseases of Cucurbit vegetables in Australia. The related tools provided at the end of the page can be used by growers and crop consultants to assist in the identification of insect pests, mites, diseases, beneficials, and disorders. They include photographs and detailed information about specific pests. For unknown pests, it is important to have an expert identify them so that they can be managed appropriately.

Cucurbits include cucumber, zucchini, pumpkin, squash, bitter melon, hairy melon, luffas, watermelon and rockmelon. A range of pests can cause damage to cucurbits, and crops need to be regularly monitored and treated when a pest becomes a problem.

Key pests and diseases of Cucurbits:

Some of the key insect and mite pests of cucurbits include:
  • Sucking pests – Aphids (e.g. Melon aphid); Whitefly; Thrips (Melon, Onion, Western flower thrips).
  • Chewing pests – Caterpillars (e.g. Heliothis, Cucumber moth); Beetles (e.g. Pumpkin beetles); Mites (e.g. Two-spotted mite); Cucumber fly.
Some key diseases include:
  • Fungal diseases – Damping off; Root rots; Alternaria leaf spot; Septoria spot; Downy mildew; Gummy stem blight; Powdery mildew; Anthracnose; Fusarium wilt; Scab
  • Bacterial diseases – Angular leaf spot; Bacterial leaf spot; Bacterial soft rot; Bacterial wilt; Brown spot
  • Viral diseases - Watermelon mosaic virus; Papaya ringspot virus; Zucchini yellow mosaic virus; Cucumber mosaic virus
Additionally cucurbits are susceptible to root-knot nematodes.

Pest management:

IPM tips for managing sucking pests:

  • Site sanitation – weeds, infested plants, crop debris must be removed
  • Use clean transplants – don’t introduce the pests
  • Monitor crops – early detection and population knowledge are a must
  • Crop-free periods may work
  • Avoid overlapping crops or kill pests in residue before planting again nearby
  • Know the pests you have or are targeting
  • Know the impacts of your insecticides on beneficials
  • Understand resistance management and chemical groups
  • Use chemical insecticides only when necessary and do not rely on them

IPM tips for managing chewing pests:

  • Use resistant varieties
  • Consider planting time of crops
  • Identify and monitor the populations of both the pests and beneficials – including eggs, small larvae, and adults
  • Understand available management options and effective bio-pesticides
  • Understand conducive environmental conditions – for pests, beneficials, and biological insecticides
  • Disrupt pest life cycles by targeting overwintering and survival sites
  • Know your acceptable limits for damage and identify when you may need to spray

IPM for nematodes:

  • Prevention
  • Avoidance – Soil testing, rotations, use of fallow periods
  • Monitoring
  • Suppression

IPM for diseases:

  • Understand the lifecycles and conducive environmental conditions for particular diseases
  • Commit to good farm hygiene practices – clean up your farm and remove all weeds, crop debris, and volunteer hosts
  • Monitor weather conditions (particularly temperature, humidity, and leaf wetness)
  • Monitor crops regularly and use predictive models
  • Use resistant varieties
  • Reduce the pathogen levels by crop rotation
  • Amend and manage soil to disadvantage fungi
  • Avoid heavily infested blocks by testing soil prior to planting
  • Exclude or eradicate the pathogen (quarantine; use of pathogen-tested seeds and propagated materials)
  • Learn how to detect early disease symptoms on your crop
  • Minimise ways in which the disease can spread on-farm – remove and destroy sick plants when symptoms first show
  • Understand chemical resistance and rotate chemical groups

Beneficials include:

  • Ladybird beetles
  • Hover flies
  • Lacewings
  • Predatory bugs, thrips and mites
  • Moth egg parasitoids, e.g. Trichogramma spp.
  • Aphid parasitoids, e.g. Aphidius spp.
  • Whitefly parasitoids, e.g Encarsia formosa
  • Insect bacterial diseases – Bacillus thuringiensis (Bt)

Source of information and related tools: