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Monitor for Spider Mites, Aphids, and Whitefly—Early Squaring

Take a combined sample for spider mites, aphids, and whitefly at least once a week and record results on the monitoring form (PDF^ 694K).

1. Beginning at least 50 paces into the field, choose a plant at random and select the 5th mainstem node leaf from the terminal. Turn the leaf over and, using a hand lens, check for insects and mites on the underside. This is called a leaf-turn.
2. Count the aphids and record the number and color (yellow or black).
3. For spider mites, note their presence or absence.
4. Check for whitefly adults; if 3 or more are found, mark the leaf as infested.
5. For whitefly nymphs, place a quarter-size leaf ring between the central and left-side main veins and check for presence or absence of large (3rd or 4th instar) nymphs.

Take a leaf-turn sample from 10 plants in 4 representative areas of the field for a total of 40 plants. Walk at least 20 paces between sample plants. Also check the field edges for whitefly migration.

Check also for natural enemies of aphids, mites, and whitefly, including parasitized aphids and whiteflies, western flower thrips, western predatory mites, bigeyed bugs, minute pirate bugs, lacewing larvae, syrphid fly larvae, and lady beetles.

Treatment thresholds

• Spider mites. Treat for spider mites if 30% to 50% of leaves show mite presence.
• Aphids. Between first square and open boll, treat for aphids if 50 to 75 aphids per 5th mainstem node leaf are present.
• Whitefly adults. Treat adults if 40% of leaves have at least 3 adults. If using IGRs, nymphs must also be present to justify treatment. If high numbers of adults are at field edges, but there are no nymphs, an edge treatment with a non-IGR may be required.
• Whitefly nymphs. Treat if 40% of leaves are infested with large nymphs.

See pest management guidelines for more details on thresholds and treatment options.

Important links

• Leaf ring sampling for whitefly nymphs
• Spider mite, aphid, whitefly monitoring form (PDF^ 694K)
• Photo guide for mites, aphids, and whitefly
• Photo guide for natural enemies of mites, aphids, and whitefly

Related Information

• Spider mites pest management guideline
• Whitefly pest management guideline
• Aphid pest management guideline

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