Diseases and pests of field vegetables in April

I. Diseases

Rhizoctonia on potatoes

Causal agent – Rhizoctonia solani

Symptoms/Damage

Dark to black sclerotia of the fungus are observed on the infected tubers. Black-brown spots appear on the sprouts of the infected tubers, which cause their death.

Life cycle

It spreads through diseased tubers; develops under monoculture cultivation and in heavy soils; survives as sclerotia on the tubers and in the soil; develops within a temperature range of 6-33°C and humidity of 30-90%.

Control

• Introduction of a 6-8 year crop rotation;
• Use of healthy planting material;
• Treatment with plant protection products (PPP);
• Registered PPP: Quadris 25 SC 300 ml/ha; Proradix 2 g/100 kg tubers (for treatment of tubers before or during planting).

Wireworms

Causal agent – Fam. Elateridae

Symptoms/Damage

The larvae bore into the tubers. As a result, they rot because pathogenic microorganisms enter through the tunnels; damaged tubers cannot be stored for a long time.

Life cycle

The larvae are most harmful at a temperature of 14-17°C and 65% field capacity.

Control

• When 6-10 larvae/sq. m are established, insecticides are applied in the furrow simultaneously with planting;
• Registered PPP: Vidate 10 G 2 kg/ha; Ercole GR 1000-1500 g/ha; Mocap 10 G (grace period for sales and distribution 22.02.2020) 2-3 kg/ha; Nemathorin 10 G 2 kg/ha; Trika Expert (soil application at planting) 1.0 - 1.5 kg/ha; Diastar Maxi GR - 1.2-1.6 kg/ha; Colombo 0.8 MG, Belem 0.8 MG - 2.4 kg/ha

Garlic fly

Causal agent – Suilia lurida

Symptoms/Damage

It attacks first the middle leaf, which later curls spirally. Second and third instar larvae destroy the youngest underdeveloped leaves and move towards the bulb. The attacked plants turn yellow and wilt. The stem is hollow and the bulb is soft. The larva is located at the base of the stem or in the bulb.

Life cycle

It develops one generation per year. It overwinters as an adult insect. Flight begins early in spring, when the average daily and soil temperatures are above zero. The flies lay their eggs at the base of the stem or on the soil near the plants.

Control

• Introduction of a 2-3 year crop rotation;
• Limiting the application of farmyard manure, which attracts the flies;
• When the flight of the flies begins, the crops are sprayed with PPP;
• There are no registered PPP against this pest. Broad-spectrum insecticides are used - Vaztak Nov 100 EC – 0.03%.

Only PPP at the registered dose, included in the “List of products for plant protection authorised for placing on the market and use”, published on the website of the BFSA, shall be applied.

PPP shall be purchased only from traders holding an authorisation for the activity and included in the list of companies authorised to carry out the activities of wholesale trade in plant protection products, retail trade in plant protection products in an agricultural pharmacy, repackaging of plant protection products and performance of fumigation and disinfection of areas, premises and plant production against pests, published on the website of the BFSA.