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Greenhouse pepper

Both of the main thrips predators used in pepper feed on pollen as well as prey: Orius needs it (UConn), and the Swirski mite breeds on it. So they can be released into a flowering crop before the pests build. The Swirski mite also takes whitefly eggs and young nymphs and broad mite, and it controlled broad mite on sweet pepper plants in a greenhouse trial (van Maanen and others, 2010).

Aphids are the pest that needs a separate plan. UC IPM notes that green peach aphid carries pepper potyviruses and cucumber mosaic virus, and that treatment thresholds for it are not well established. For reducing virus spread it points to sanitation, not natural enemies, and on cucurbits it states that biological control does not reduce aphid virus transmission. Start the aphid parasitoids soon after planting, screen the vents, and destroy old crop debris and alternate host plants, which UC IPM counts as an important factor in reducing virus spread.

crop context · sweet pepper house

The pests that matter in a pepper house

ONCE FLOWERING

Western flower thrips

Feeding scars the fruit. Pepper has the best evidence for Orius: in Florida field work, one bug to about 40 thrips held numbers below the economic threshold.

ReleaseOrius insidiosus0.5–10 /m² per release, repeated once or twice

SOON AFTER PLANTING

Green peach aphid

Colonies build under the newer leaves, honeydew fouls the fruit and it carries pepper viruses. Use Aphidius ervi if potato aphid turns up.

ReleaseAphidius colemani0.25–4 /m² per release, at least three releases

EARLY, BEFORE DAMAGE

Broad mite

Leaves turn down and go coppery, side buds break in a tuft and fruit is discoloured where they feed. Damage shows weeks after the mites arrive.

ReleaseAmblyseius swirskiiHot-spot rate, 100–300 /m², concentrated on the shoot tips

AT THE FIRST MITES

Two-spotted spider mite

Stippling and webbing in hot, dry parts of the house. Release at the first mites found and repeat.

ReleasePhytoseiulus persimilis2–50 /m² per release (Koppert); 100+ /m² on hot spots (Biobest)

AT THE FIRST WHITEFLY

Greenhouse whitefly

The Swirski mite eats whitefly eggs and young nymphs, and pepper is one of the crops it is used in. The same release also covers thrips.

ReleaseAmblyseius swirskii25–100 /m² per release (UF/IFAS range), or sachets

FROM PLANTING

Chilli thrips

Bronzes and curls new growth. Pepper is one of its favourite hosts. UF/IFAS reports significant damage in Florida and Texas.

ReleaseAmblyseius swirskii25–100 /m² per release; 100–300 /m² on hot spots

Season calendar

US SEASONALITY · QUALITATIVE · HEATING SHIFTS IT

	J	F	M	A	M	J	J	A	S	O	N	D
Western flower thrips	Jan: Quiet	Feb: Quiet	Mar: Quiet	Apr: Building	May: Pest pressure high	Jun: Pest pressure high	Jul: Pest pressure high	Aug: Pest pressure high	Sep: Building	Oct: Building	Nov: Quiet	Dec: Quiet
Aphids	Jan: Quiet	Feb: Quiet	Mar: Quiet	Apr: Building	May: Pest pressure high	Jun: Pest pressure high	Jul: Pest pressure high	Aug: Building	Sep: Building	Oct: Building	Nov: Quiet	Dec: Quiet
Broad mite	Jan: Quiet	Feb: Quiet	Mar: Building	Apr: Building	May: Pest pressure high	Jun: Pest pressure high	Jul: Pest pressure high	Aug: Pest pressure high	Sep: Pest pressure high	Oct: Building	Nov: Quiet	Dec: Quiet
Spider mite	Jan: Quiet	Feb: Quiet	Mar: Quiet	Apr: Quiet	May: Building	Jun: Pest pressure high	Jul: Pest pressure high	Aug: Pest pressure high	Sep: Pest pressure high	Oct: Quiet	Nov: Quiet	Dec: Quiet

Pest pressure high
Building
Release window
Quiet

Western flower thrips · high pressure May–Aug
Aphids · high pressure May–Jul
Broad mite · high pressure May–Sep
Spider mite · high pressure Jun–Sep

Starter program

A starting point for a first season, assuming the house has no residual insecticide and no resident pest populations. Adjust the rates to your own scouting counts and your supplier's advice.

AT PLANTINGAmblyseius swirskii25 /m² preventive, 50 /m² at the first thrips, 100–300 /m² on hot spots; replace sachets after four weeks
SOON AFTER PLANTINGAphidius colemani0.25–4 /m² per release, at least three releases, before aphids build
ONCE FLOWERINGOrius insidiosus1–2 /m² per release, up to 10 /m² on hot spots, in long days (over about 14 hours); repeat once or twice
ON BROAD MITEAmblyseius swirskii100–300 /m² concentrated on the shoot tips of affected plants
AT FIRST MITESPhytoseiulus persimilis2–50 /m² per release, repeated weekly at least twice where mites are established

Size this program for your area →

Setting the house up

Most of what decides a release program is the house itself: what was sprayed, the climate, and what gets in through the vents.

Give Orius time

UConn warns that Orius can take up to 8–10 weeks to establish, and it is most effective at 68–85 °F (20–29 °C). That slow start is why it goes in early in the flowering crop, not into a thrips outbreak.

Keep the house warm enough for the Swirski mite

Koppert says it is not effective below 64 °F (18 °C), and it is sensitive to humidity below 60 %.

Screen the vents to the right size

UC IPM gives 0.355 mm (355 microns) or finer to keep out winged aphids, and 0.145 mm or finer for western flower thrips. Fine screen restricts airflow, so add screen area or adjust the ventilation.

Clear old crop and weeds

UC IPM names field sanitation, destroying crop debris right after harvest and removing alternate host plants, as an important factor in reducing virus spread in pepper, though it does little against the aphid itself. Releases do not stop virus spread either, so sanitation is part of the aphid plan.