Strawberry diseases and pests.
The most dangerous disease of strawberries is gray mold caused by the fungus Botrytis cinerea, which infects all the organs of the plant. It strikes the flowers first, which turn brown and wither. The fungus spreads from the affected parts of the flower to the fruit. The first symptoms of the disease are brown spots on the fruit, spreading over the whole fruit and causing it to rot. In humid weather, rotting fruit turns grayish, thick coating. This disease is counteracted, keeping the strawberry plantation clean. Dead plant debris should be removed and sprayed. The first spraying is done, if 10% flowers are in the white bud stage, next in increments of every 7 days until the moment, when z 10% the petals fall off the flowers. The most effective measure is Euparen in concentration 0,25%, then Sadoplon 0,3%.
In wet summers, strawberries are attacked by white leaf spot, which destroys the leaves and thus reduces plant growth. In places of infection, small ones are formed on the leaves, roundish, gray-white spots, surrounded by a purple border. Sick leaves turn yellow and die quickly.
Strawberry leaves are also infested with red blotch, which also occurs on flower stalks and sepals. Small ones are formed on the leaves, purple carmine, roundish patches causing yellow-red discoloration of the tissue, first around the spots, and then the whole plate. Heavily infested leaves dry up.
Powdery mildew causes great damage in the cultivation of strawberries, which destroys young seedlings, as well as masters the flowers, fruit buds and lowers the value of ripe fruit. A characteristic symptom of this disease is a mealy coating, occurring mainly on the lower side of the leaves. Combating white and red leaf spot and powdery mildew in strawberries mainly consists in removing and destroying last year's leaves in the spring, on which these mushrooms winter, early removal of weeds and mowing the leaves after harvesting the fruit. We fight highly intensified diseases chemically with two fungicides used against gray mold, and spraying is used in this case as well 1-2 times after harvesting the fruit.
Of the pests, black can cause great losses, a flower raspberry beetle covered with delicate gray hair. It damages the flowers, because the female of this insect lays eggs to flower buds and then cuts the peduncle under the bud, which breaks. The browned bud initially hangs downwards, then falls to the ground. The larvae feed in the buds, a po 3-4 weeks they pupate. Young beetles appear in June, they forage through 2-3 weeks on the leaves, nibbling in them slight, round buttonholes, and then take refuge in winter hideouts. In the period of the appearance of beetles, when the buds in the inflorescences loosen, plants are sprayed with Owadofos Pł. 50 in concentration 0,15%.
Other pests that attack strawberries can do more damage: strawberry mite and hop spider mite.
The mite is invisible to the naked eye. It eats the juices sucked from developing leaves and other organs, destroying numerous cells. As a result of feeding this parasite, plant growth is inhibited, discoloration and distortion of the leaves, inflorescences and fruit. Controlled plants give a low yield of small and misshapen fruits or too, due to flower distortions, they do not bear fruit at all. The pest is difficult to fight. It is recommended - to reduce the number of mites – mowing the leaves after harvesting the fruit.
The spider mite is a pest of many plants. On strawberries, it mainly feeds on the underside of the leaf blades, which spins the delicate cobwebs. As a result of the suction of the cell contents and the changes taking place in them, small yellow-green discoloration first appears, then all leaves turn brown and dry. This has a negative impact on fruiting. It is combated by spraying Roztoczol ex. Pł. 8 in concentration 0,2% or Torque in concentration 0,05%. It is sprayed basically before flowering and after harvesting the fruit.