Apple and pear scab (Venturia inaequalis;Venturia pirina)

The period when fruit trees are in the phenological development stages “bud swelling”, “bud break” and “mouse ear”, poses a risk for the development of a number of diseases and the multiplication of many pests in pome fruit species.

On the lower side of the leaves, irregular olive-green spots with a green-brown coating are formed, while on the upper side – clearly outlined spots with a grey periphery and an olive-brown centre. On the fruit set and fruits up to the size of a walnut, spots with a velvety coating, deformation, cracking, and fruit drop are observed, and on already formed fruits – scabs and deformations.

The primary infections by the disease are caused by the ascospores of the pathogen, which are found in the soil and are ejected under conditions of abundant soil moisture, air temperature above 5°C and establishment of the crop phenophase “mouse ear”. Symptoms on the leaves appear immediately after bud break.

Strategy for pest control

To reduce primary infections from ascospores at this stage of crop vegetation, it is important to carry out the first preventive spraying.

Authorised plant protection products

Apple:

shampion WP (Macc 50 WP, Shamp WP) – 0.3%; Cuproxat FL – 0.3%; Captan 50 WP – 0.2%; Captan 80 WP – 150–180 g/ha; Merpan 80 WDG – 0.15%; Manfil 75 WG – 320 g/ha; Dithane M-45 – 200 g/ha; Dithane DG – 200 g/ha; Sancozeb 80 WP – 200 g/ha; Polyram DF – 0.2%/ha.

Pear:

shampion WP (Macc 50 WP, Shamp WP) – 300 ml/ha; Cuproxat FL – 300 ml/ha; Captan 80 WP – 150–180 g/ha; Manfil 75 WG – 320 g/ha; Dithane M-45 – 200 g/ha; Dithane DG – 200 g/ha; Sancozeb 80 WP – 200 g/ha; Scab 80 WG – 188 g/ha; Bordeaux Mix 20 WP – 375–500 g/ha; Kocide 2000 WG – 155–680 g/ha; Funguran OH 50 WP – 150–250 g/ha; Vitra 50 WP/ Cuprohigh 50 WP – 150 g/ha; Polyram DF – 200 g/ha.

Biological control

The antagonistic fungi Athelia bom-basika and Chaetomium globosum inhibit the formation of ascospores of V. inequalis.