How can spider mites be identified on cucumbers in a greenhouse? - briefly
Look for fine yellow or white stippling on leaf surfaces, tiny moving dots visible under magnification, and delicate webbing on the undersides of leaves. Confirm presence by inspecting the lower leaf side with a hand lens or microscope for the characteristic eight‑legged, oval‑shaped mites.
How can spider mites be identified on cucumbers in a greenhouse? - in detail
Spider mites on cucumber crops in protected cultivation reveal themselves through distinct visual cues and measurable signs.
Leaf discoloration appears first as tiny, pale speckles that enlarge into stippled patterns. As feeding continues, the tissue turns bronze or yellow, and the affected area may curl or become brittle. Webbing is a reliable indicator; fine silk threads connect colonies on the undersides of leaves, stems, and fruit. In severe infestations, the web becomes dense enough to obscure the leaf surface.
Direct observation requires magnification. A hand lens of 10‑30× reveals the mites as oval, reddish‑brown organisms about 0.4 mm in length. Key morphological features include:
- Four pairs of legs, each ending in two long setae.
- A globular body divided into two sections (prosoma and opisthosoma).
- Absence of eyes, distinguishing them from thrips.
Sampling procedures improve detection accuracy. Cut a 5‑cm leaf segment from the lower canopy, place it in a zip‑lock bag, and examine it under a stereomicroscope within 30 minutes. Count mites per leaf area to assess population density.
Sticky traps provide early warning. Yellow adhesive cards positioned at canopy height capture dispersing adults. A sudden increase in trap captures precedes visible damage, allowing pre‑emptive action.
Environmental monitoring supports diagnosis. Spider mite activity rises when relative humidity falls below 50 % and temperatures exceed 25 °C. Recording these parameters helps correlate symptom onset with favorable conditions for the pest.
Chemical or biological control decisions depend on accurate identification. Confirming the presence of spider mites through the described visual and microscopic criteria prevents unnecessary pesticide applications and guides integrated pest‑management strategies.