Plant protection of sweet and sour cherries in May

Cherry and sour cherry are sprayed twice during this period against cylindrosporiosis (white rust), brown rot and cherry fruit fly. Effective fungicides against cylindrosporiosis are: Karomat 2.5 EW – 300 ml/da, Signum WG – 30 g/da, Score 250 EC – 30 ml/da, Syllit 40 SC – 150 ml/da, Syllit 544 SC – 125 ml/da, Delan 700 WG – 0.05% and Flint Max 75 WG – 30 g/da. Among the listed fungicides, Karomat 2.5 EW – 300 ml/da and Signum WG – 65-70 g/da are also effective against brown rot. At the first spraying against cylindrosporiosis, in cases of high density of leaf-feeding caterpillars, sawflies on stone fruit and weevils, Meteor 60-90 ml/da is added to the fungicidal solution. Usually, the spraying against the cherry fruit fly coincides with the second spraying against cylindrosporiosis. For control of the cherry fruit fly, one of the insecticides authorized for use against this pest is added to the fungicidal solution: Decis 100 EC – 10-17.5 ml/da, Imidan 50 WG – 150 g/da, Calypso 480 SC – 20 ml/da, Karate Zeon 5 CS – 15 ml/da, Naturalis – 100-200 ml/da.

Only for late-ripening cherry cultivars and very high density of the cherry fruit fly is it necessary to carry out a second spraying against it. This is done 10-14 days after the first one. Young, non-bearing cherry and sour cherry trees are sprayed against aphids. Effective insecticides against them are: Decis 100 EC – 12.25 ml/da, Mospilan 20 SG – 25 g/da, Closer 120 SC – 20 ml/da, Lamadex Extra – 40-60 g/da, Teppeki – 14 g/da.

In case of frequent showers during the fruit ripening period and the presence of severe infection with brown rot, it is necessary to carry out one or two sprayings against the pathogen. Effective fungicides are: Indar 5 EW – 150 ml/da, Karomat 2.5 EW – 300 ml/da, Luna Experience – 50 ml/da, Password 25 WG – 50 g/da, Signum WG – 30 g/da, Chorus 50 WG – 40-50 g/da.

It is very important to observe the pre-harvest interval at the last spraying against brown rot.

In May it is also necessary to take measures against fruit cracking in cherry, which is also a cause for attack by rot pathogens. There are data from different countries, where cracking is a problem, that spraying with CaCl₂ reduces the percentage of cracked fruits. Usually it is recommended to carry out three sprayings with 0.5% CaCl₂ during the fruit ripening period. 

Foliar fertilizers containing calcium are also recommended – Vuxal Calcium – 500-600 ml/da, applied with 150 l spray solution. Three to four treatments are carried out, the first being done about 8 weeks before harvest. According to the company producing Vuxal Calcium, this foliar fertilizer is compatible with the pesticides commonly used in cherry.

In a number of European countries and in the USA, spraying is also carried out against cracking with: RainGard – it contains fatty acids, plant esters, emulsifiers and water. When sprayed, it forms a film on the fruit skin, which is a barrier to the penetration of rainwater and thus prevents cracking. Four to five sprayings are recommended, the first being done at the “clearing” of the fruits or when they colour to a straw-yellow shade, and the remaining ones at intervals of 7-10 days. It has been established that this product reduces cracking by 50%;

SureSeal - a copolymer of stearic acid, cellulose and calcium, which forms a biofilm on cherry fruits and protects them from cracking. A double spraying is recommended – 4 and 2 weeks before harvest.

For effective plant protection it is necessary:

Sprayings to be carried out in accordance with the warnings of the Regional Food Safety Directorates and the advice of plant protection agronomists;

To use only pesticides that are authorized for use, and sprayings to be carried out only when pest density exceeds the established economic injury thresholds, which are for:

Cherry fruit fly – 10 flies/trap.

In organic production the use of synthetic pesticides is not permitted. For control of fungal diseases, copper-containing and sulphur-containing fungicides are used. For pest control, the following bioinsecticides are approved:

Naturalis against whitefly and spider mite in strawberry, cherry fruit fly, pear psylla, European red mite.

Pheromones (attractants) are also approved:

For cherry fruit fly, the visual trap Farkon AM is approved.