Bacterial blight of apple fruit is caused by the parasitic bacterium Erwinia amylovora. This disease originates from North America, where it caused enormous damage, which is why pear cultivation in some parts of the USA and Canada has practically stopped. It did not appear in Europe until 1957, when it was first discovered in England. Since then, it has spread to many countries, and it was first recorded in Serbia in 1990. Bacterial blight is the most significant disease of apple fruit species of bacterial origin and causes great economic losses in the cultivation of these crops.
Symptoms of the disease
This disease attacks all parts of the pear, apple and quince: it starts with the flowers and leaves, then moves to the leaves, young fruits and even thicker branches, trunk and bark. In the spring, 2 to 3 weeks after flowering, the flowers first turn brown, then turn black and dry. Diseased leaves do not fall, but remain on the branches. The leaves first wither, turn brown, and then turn black, looking as if they were engulfed in flames, which explains the name “flame plant”. Softer, swollen and cracked surfaces can be seen on infected branches. One of the most characteristic symptoms is the appearance of a shepherd’s rod and drops of bacterial exudate, in which the bacteria hibernates.
How does the disease spread?
In early spring, with the beginning of the movement of juices, the bacterium becomes active and begins to infect larger and larger parts of the plant tissue, often destroying the entire fruit tree. The parasite spreads rapidly thanks to bacterial exudate, insects and humans (during pruning). The bacterium penetrates into plant tissues through stomata openings of leaves, young fruits, lenticels, openings of nectar glands, as well as through injuries and wounds.
Factors favoring the spread of disease
Warm and humid weather create ideal conditions for the spread of bacteria. Once the pathogen is established in the plants, it remains present. Therefore, regular inspection of orchards and maintenance of maximum hygiene during agrotechnical measures is of crucial importance. Infected branches should be pruned at least 30 cm below the diseased area and removed from the field, then burned. If the branches are diseased along the entire length to the conductor, it is necessary to remove the entire tree.
Recommendation for disease control
Application of biobactericide ERWIX preparation in a concentration of 1%.
This preparation is registered for the control of the bacterium Erwinia amylovora and works by preventing the settlement of the bacterium, its survival and infection of the plant by destroying its biofilm. Treatments should be carried out 2 to 3 times, starting from the beginning of flowering until the end of flowering.
The effectiveness of ERWIX preparations in controlling this phytopathogenic bacterium has been proven both in laboratory and field conditions.
In this way, you can effectively control bacterial blight and protect your orchards from significant losses.
