Diseases of Fruit Plantation Medicinal and Aromatic Crops

Fabraea leaf spot

Causal organism: Fabraea maculata
Symptoms

• Leaf :spot can be found on petioles, leaves, shoots and fruits. Initial lesions on leaves are tiny, round, purplish-black spots which quickly enlarge to 1/8th - 1/4th inch in diameter and usually have a blackish-brown center (photo 2-46). Spots coalesce and severely infected leaves fall to the ground prematurely. A small black acervulus may develop at the centre of each lesion,from which conidia ooze out in a creamy, white mass in wet weather.
• Fruit :lesions (photo 2-47) are larger than those on leaves and cause the fruit to crack and drop. Lesions on current season's shoots may be observed as small inconspicuous, purplish-black spots. Some lesions develop into superficial cankers, but most are walled-off during the next growing season, as the cankers rarely persist in two-year-old wood.
Disease Cycle

The four-celled conidia (Entomosporium maculatum), with a distinctive insect-like appearance, are spread mainly from overwintering leaf litter, and some from twig cankers, by splashing water from rains or overhead irrigation. Wetting periods for infection may vary from 8 to 12 hours at a temperature range of 10°C-25° C. Lesions begin to appear about 7 days after the beginning of an infection period. The disease may advance rapidly in late summer as wind and rain distribute the conidia throughout the tree. Susceptibility of leaves and fruit to infection does not decrease with maturity. Nearly all pear of European descent are susceptible to this leaf spot.





Management

• This disease can be controlled by using protectant fungicides.
• Early-season spray shedule for pear scab should also control early-season leaf spot infections. Where ascospores and conidia of the fungus develop after petal fall, summer fungicide treatments are needed