Pest control system for onions

Pest – Onion fly Delia antiqua

Damage

The hatched larvae bore into the base of the leaves, gnaw a gallery in the stem and move into the bulb. Damaged plants lag in growth, turn yellow, lodge, can be easily pulled out, and eventually dry up. As a result of the damage, the tissues ferment and emit an unpleasant smell of rotten onion.

Control

The beginning of the flight of the flies is expected in the second ten-day period of April. Infested plants must be immediately removed and destroyed. The first treatment should be carried out during the period of mass flight, which coincides with the flowering of sour cherry. Economic injury threshold: 5 flies/10 sweeps with an entomological net.

Pest – Tobacco thrips Thrips tabaci

Damage

Thrips suck sap from the leaves and whitish spots appear on them. Under heavy infestation the spots merge and the entire leaf turns white. On the spots small black dots can be observed – the pest’s excrement.

Control

In April, attention should be paid to tobacco thrips from the very beginning of its appearance, when it moves from plant residues or weeds onto the onion.

Pest – Downy mildew Peronospora destructor

Damage

Chlorotic to light green, elliptical spots appear on the leaves, which, in humid weather, are covered with a violet sporulating growth. Favourable conditions for infection are created at temperatures of 3–25 ºC and the presence of water droplets retained on the plants. 

Control

Eradication of volunteer and primary infected plants. Upon detection of the first spots of the disease, vegetation treatments should be carried out. In periods of dry weather, treatments may be performed less frequently.

When treating onion crops, an adjuvant should be added!