Pest control system for stone fruit species in May

Phenological stage of development – fruit growth

Pest – Shot hole disease gen. Stigmina, Pseudomonas, Xanthomonas

Damage

The symptoms of the disease on sweet and sour cherry fruits appear in the form of dark spots which, during ripening, become depressed and in most cases adhere to the stone. On apricot and peach fruits, the spotting appears as small to larger, reddish-brown scabby patches.

Control

The expected precipitation at the beginning and during the third ten-day period of May may trigger a significant infection wave (the spread and germination of spores occurs via rain), therefore it is necessary to carry out preventive sprays every seven days with one of the registered plant protection products.

Pest – Blossom blight / early brown rot Monilinia laxa

Damage

The symptoms of the disease on young fruit sets are observed in the form of local brown rot, which gradually affects the entire fruit. The damaged plant parts do not drop but remain on the tree until the following spring.

Control

Vegetation treatments are carried out when conditions for infection are present, using registered plant protection products at 8–10-day intervals, while carefully observing the pre-harvest intervals of the applied fungicides and the fruit harvest time.

Pest – Cherry leaf spot (cylindrosporiosis) in sweet and sour cherry Blumeriella jappii

Damage

On the upper side of the leaves the symptoms appear as numerous small, purplish dots, which subsequently turn into necrotic spots. In humid weather, whitish pustules form on the underside of the affected leaves. Under heavy infestation the leaves turn yellow and fall off.

Control

Under favourable climatic conditions (rain and warm weather) during May, cherry leaf spot may spread massively. In orchards with established infection, sprays with authorised plant protection products should be continued in order to limit the spread of the disease, while monitoring the residual effect of the fungicide used.

Pest – Powdery mildew of peach Sphaerotheca pannosa

Damage

The pathogen causes irregularly shaped spots on the leaves, and a dense white coating appears on the underside of the leaf blade. On the shoots, the mycelial coating causes their deformation and the affected twigs become distorted. The disease also attacks green fruits, forming a white to brown mouldy coating on them.

Control

The pathogen develops both in humid and in dry weather, but frequent and abundant rainfall significantly suppresses the development of the disease. Vegetation treatments are carried out upon detection of the first spots, at intervals of 10–12 days until fruit enlargement, using authorised plant protection products.

Pests

Pest – Cherry fruit fly Rhagoletis cerasi

Damage

The fly is active during the day at temperatures above 18°C. It lays its eggs in fruits that have started to ripen. Damage is caused by the larva, which feeds on the fleshy part of the fruit. The damaged fruits darken, rot and become depressed at the site of damage.

Control

Chemical control of the cherry fruit fly is carried out against adults before they lay their eggs, approximately 10–12 days after the beginning of flight. Registered plant protection products with a short pre-harvest interval, consistent with the harvest dates, should be used.

Pest – Plum fruit moth Laspeyresia funebranа = Grapholita (Aspila) funebrana

Damage

The moths fly early in the morning, and the females lay their eggs mainly on the young fruits. After hatching, the young larva bores into the fruit immediately next to the place where the egg was laid. It feeds on the fleshy part, making galleries directed towards the stalk. The damaged fruits stop growing, acquire a violet hue and after some time fall off together with the larvae.

Control

Chemical treatment is carried out against adults before egg-laying with insect growth regulators (chitin synthesis inhibitors) at an economic injury level of 2–3 moths/trap/week, and against larvae at the time of hatching and boring (approximately 2–3 weeks after moth emergence), with contact insecticides at an economic injury level of 1–1.5% fresh entries.

Pest – Oriental fruit moth  Grapholitha molesta

Damage

The flight and egg-laying period of the first generation continues until the end of May. The hatched larvae bore mainly into young shoots through the terminal bud and feed on the green, non-lignified tissue. The damaged shoots wilt, dry out, and gummosis is observed at the site of damage.

Control

Chemical control is carried out at the end of moth flight and the beginning of larval hatching, using contact insecticides, upon reaching the economic injury level of:

•  young orchards – 1–1.5% infested twigs;

• fruit-bearing orchards – 1.5% damaged shoots and fruits.

Pest – Peach twig borer Anarsia lineatella

Damage

During the month, moths of the first generation of the pest are in flight. The females lay their eggs singly on the leaves and shoots. The larvae, in addition to shoots, also attack the fruits. One larva damages 1–2 shoots and one fruit.

Control

Upon reaching the economic injury level of:

• 3% damaged shoots and fruits by the larvae, chemical treatment should be carried out with one of the authorised plant protection products.