Vulnerability of sweet cherry cultivars to continuous periods of spring frosts in Plovdiv, Bulgaria

S. Malchev, S. Savchovska*

Fruit Growing Institute – Plovdiv, 12 Ostromila Str., 4004 Plovdiv, Bulgaria

(Manuscript received 31 August 2020; accepted for publication 16 October 2020)

Abstract. The periods with continuous freezing air temperatures reported during the spring of 2020 (13 incidents) affected a wide range of local and introduced sweet cherry cultivars in the region of Plovdiv. They vary from -0.6°C on March 02 to -4.9°C on March 16-17. The duration of influence of the lowest temperatures is 6 and 12 hours between March 16 and 17. The inspection of fruit buds and flowers was conducted twice (on March 26 and April 08) at different phenological stages after continuous waves of cold weather conditions alternated with high temperatures. During the phenological phase ‘bud burst’ (tight cluster or BBCH 55) some of the flowers in the buds did not develop further making the damage hardly detectable. The most damaged are hybrid El.28-21 (95.00%), ‘Van’ (91.89%) and ‘Bing’ (89.41%) and from the next group ‘Lapins’ (85.98%) and ‘Rosita’ (83.33%). A larger intermediate group form ‘Kossara’ (81.67%), ‘Rozalina’ (76.00%), ‘Sunburst’ (75.00%), ‘Bigarreau Burlat’ (69.11%) and ‘Kuklenska belitza’ (66.67%). Candidate-cultivar El.17-90 ‘Asparuh’ has the lowest frost damage values of 55.00% and El.17-37 ‘Tzvetina’ with damage of 50.60%.

Tomato leaf miner, Tuta absoluta (Povolny) (Lepidoptera: gelechiidae) – first record in Bulgaria

The tomato leaf miner Tuta absoluta (Povolny) is the most damaging pest of tomatoes in South America. In 2006 the pest was introduced by accident
in Spain and since then it has invaded many countries in South Europe and the Mediterranean region. In 2009 there were official reports for new invasions from
Greece, Switzerland, Malta, Portugal, Albania, France, Italy, Libya and countries from the Gulf region – Bahrain and Kuwait. In Bulgaria the National Service of
Plant Protection (NSPP) undertook a national survey for the detection of the tomato leaf miner using pheromone traps. On 16 October 2009 an official
statement was published on the website of NSPP for the presence of the tomato leaf miner in several glasshouses and in the field in South Bulgaria. At a
glasshouse with tomatoes near Plovdiv we observed a severe infestation by the pest which has rapidly spread after the last treatment with pesticides at the end
of August. The leaves were the most heavily damaged plant parts with an average of 9.42 and 8.75 mines per leaflet on the middle and upper layer of the canopy
resp., followed by the fruits. No damage on the stems was observed. Description of the pest stages, behavior, monitoring, prevention and control of the pest are
discussed.

Tomato leaf miner, Tuta absoluta (Povolny) (Lepidoptera: gelechiidae) – first record in Bulgaria

V. Harizanova, A. Stoeva, M. Mohamedova