SUMMARY Colletotrichum gloeosporioides, Colletotrichum acutatum, Colletotrichum coccodes, andColletotrichum dematium are the four main species of Colletotrichum that cause tomato anthracnose. In Serbia, the occurrence of anthracnose on tomato fruit has been recorded during the last several years. Typical fruit symptoms include dark, sunken, and circular lesion with orange conidial masses. Pathogen isolates were obtained from a diseased tomato fruits, on PDA medium forming a white to gray colonies. The cultures developed black acervuli around the center of the colony. Conidia were hyaline, aseptate, and fusiform or rarely cylindrical. Appressoria were smooth, simple, clavate to ovate, and varied from light to dark brown. Pathogenicity tests with representative isolates were conducted on symptomless, detached tomato fruits. All tested isolates caused anthracnose lesions on tomato fruit after 7 days of incubation. Koch's postulates were fulfilled by reisolation from inoculated tomato fruits. PCR analysis (using species-specific primer pair, CaInt2/ ITS4) of genomic DNA from tomato isolates resulted in an amplification product of 490 bp, specific for C. acutatum, further confirming the identity of the pathogen. Based on morphological and molecular characteristics, the isolates from tomato fruit were determined as C. acutatum.

Plants of alfalfa (Medicago sativa) exhibiting general stunting, proliferation and phyllody associated with leaf yellowing and reddening were observed in three localities of Central Serbia. Phytoplasma strains belonging to 16SrIII-B and 16SrXII-A groups were detected and identified by RFLP and sequence analysis of 16S rDNA. Stolbur phytoplasma tuf gene RFLP analysis showed the presence of the TufAY-b-type phytoplasma subgroup in 80% of symptomatic samples. This is the first report of 16SrIII-B and 16SrXII-A phytoplasma groups affecting alfalfa in Serbia.

Unusual blight-like symptoms appeared on highbush blueberry plants in Serbia during August 2015 and infected plants showed browning and reddening of leaves, drying of foliage, and brown discoloration of internal vascular stem tissues. The objective of this study was to isolate and confirm a causal agent of the disease. Five diseased blueberry plants (2-yr-old), with visible brown discoloration in the wood, were collected for isolation on potato dextrose agar (PDA). Morphological analysis of the selected fungal isolates showed the presence of abundant black, round to oblong, or irregularly-shaped microsclerotia immersed in the PDA. Dark, globose pycnidia formed on water agar with an initially hyaline, granular content and single-celled conidia, indicating the presence of plant pathogenic fungus Macrophomina phaseolina associated with symptomatic plant tissues. Pathogenicity was confirmed on potted blueberry plants based on the initial symptoms of leaves turning yellowish to brown at the leaf edges, followed by the defoliation of leaves of the inoculated stems. Discoloration of vascular tissues was also observed on transverse sections of inoculated stems. The pathogen M. phaseolina was confirmed using molecular analysis of the ITS1-5.8S-ITS2 region of rDNA and a part of the TEF-1α gene region. This is the first report of M. phaseolina causing a blight disease on highbush blueberry in Serbia. The study should help in elucidating disease symptomatology and provide the knowledge on the risk which this fungus could pose in blueberry production.

The essential oil of Lavandula stoechas was examined by GC and GC-MS. Discs (5 mmi.d.) of the tested fungi (Alternaria alternata, Fusarium oxysporum and Botritys cinerea) were inoculated separately onto each assay plate and incubated at 25 o C for 7 days. The oil yield of dried parts (v/dw) obtained by hydrodistillation was 2.9%. Thirty-two compounds representing 98.3% of the essential oil were determined. Linalool (49.9%), linalyl acetate (14.4%), lavandulyl acetate (5.7%), α-terpineol (5.6%), terpinene-4-ol (5.1%), lavandulol (3.7%), (E)-β-ocimene (2.6%) and (Z)-β-ocimene (2.4%) were identified as the main constituents of the oil. In addition, both doses of the lavender oil showed varying levels of inhibitory effects on the mycelial growth of tested fungi used in the experiment. The results demonstrated the strongest effect on B.cinerea, followed by A.alternata and F.oxysporum. The inhibitory effect is probably dependent on the concentration of essential oils.

Bacterial leaf spot caused by the plant pathogenic bacterium Pseudomonas syringae pv. coriandricola (Psc) was observed on carrot, parsnip, and parsley grown on a vegetable farm in the Vojvodina Province of Serbia. Nonfluorescent bacterial colonies were isolated from diseased leaves and characterized using different molecular techniques. Repetitive element PCR fingerprinting with five oligonucleotide primers (BOX, ERIC, GTG5, REP, and SERE) and the randomly amplified polymorphic DNA-PCR with the M13 primer revealed identical fingerprint patterns for all tested strains. Multilocus sequence analysis of four housekeeping genes (gapA, gltA, gyrB, and rpoD) showed a high degree (99.8 to 100%) of homology with sequences of Psc strains deposited in the Plant-Associated Microbes Database and NCBI database. The tested strains caused bacterial leaf spot symptoms on all three host plants. Host-strain specificity was not found in cross-pathogenicity tests, but the plant response (peroxidase induction and chlorophyll bleaching) was more pronounced in carrot and parsley than in parsnip.