Canola/rapeseed (Brassica napus L.) is a new crop in Iran, grown since 1996. In 2006, 180,000 ha were planted. During the same year, leaf and upper stem lesions (3) were observed on cv. Hyola 401 at rosette and flowering stages in the Gorgan Province in northern Iran. Field disease incidence ranged from 1 to 40%. Several isolates from stem lesions were sent to the Department of Plant Science, Blackleg Research Lab, University of Manitoba, Canada from the Agricultural and Natural Resources Research Center of Golestan Province of Iran for pathogenicity group identification. The blackleg pathogen is divided into several pathogenicity groups on the basis of phenotypic interaction (IP) of isolates on differential cvs. Westar, Glacier, and Quinta. Isolates PG2, PG3, PG4, and PGT are highly virulent, but PG1, which recently has been named Leptosphaeria biglobosa (2), is weakly virulent. Colonies of the blackleg pathogen were reisolated from their original medium, potato dextrose agar, and grown onV8 agar medium and incubated under light for 2 weeks. Pure cultures of the pathogen were then characterized by colony morphology, pycnidia, and measurement and microscopic observation of pycnidio-spores. Fungal colonies formed with concentric rings containing pycnidia with pink ooze on V8 agar. Pycnidia were globose and as much as 200 μ 200 μm. They had a prominent beak on the ascomata that was enlarged, cylindrical, central, terete, erect, and 150 to 200 × 100 μm. Pycnidiospores were cylindrical, straight, 4 to 5 × 2 μm, and hyaline (2). To identify the pathogenicity group of the Iranian isolates, pycnidiospores were harvested from single-spore cultures after 14 days of incubation under continuous cool-white fluorescent light (1). One-week-old cotyledons from the differential cvs. Westar, Glacier, and Quinta were inoculated with pycnidiospore suspension concentration of 2 × 107 spores per ml of the four Iranian isolates. Each cotyledon lobe was punctured with forceps and inoculated with a 10-μl droplet of spore suspension. Disease evaluations were made 10 to 14 days after inoculation using a 0 to 9 rating scale. Inoculations were repeated twice with identical results yielding only the PG1 type reaction. To our knowledge, this is the first report of the presence of L. biglobosa (PG1; B-type) on canola in Iran. Differential testing fulfilled Koch's postulates. L. biglobosa seems to be less damaging compared with L. maculans, but severe phoma stem lesion epidemics have been associated with the L. biglobosa in Poland (3). The importance of this weakly virulent pathogen, whenever the relative humidity increases, has been demonstrated in greenhouse conditions (A. El-Hadrami, W. G. D. Fernando, and F. Daayf, unpublished data). Since the relative humidity in northern Iran is high, an epidemic may occur if appropriate management practices are not utilized to minimize inoculum levels. References: (1) W. G. D. Fernando and Y. Chen. Plant Dis. 87:1268, 2003. (2) R. A. Shoemaker and H. Brun. Can. J. Bot. 79:412, 2003. (3) J. S.West et al. Plant Pathol. 48:161, 2001.

In December 2008, infected leaves of Trichosanthes cucumerina were observed on commercial cucurbit farms located in Pontian, Johor (south of West Malaysia). Bright yellow and small necrotic lesions were observed on the adaxial surface of the leaves, whereas sporangiophores were observed on pale yellowish brown-to-brown lesions on the abaxial surface. The length and width of the sporangia ranged from 19 to 36 μm (28.6) and 11 to 23 μm (17.6), respectively. The length of the sporangiophores ranged from 310 to 450 μm, with an average length of 380 μm. The pathogen was identified as Pseudoperonospora cubensis on the basis of the morphological criteria described by Palti and Cohen (2). To confirm the morphological findings, DNA was extracted from symptomatic tissue and the internal transcribed spacer (ITS) region was PCR amplified using primers ITS5-P2 and ITS4 (3). The appropriate-sized amplicon was gel excised and column purified and then submitted for direct sequencing. The resulting 802 bp amplified ITS region was 100% identical to published P. cubensis sequences (GenBank Accession Nos. EU876603, EU876584, and AY198306). This sequence was deposited with NCBI GenBank under the Accession No. GU233293. In this study, pathogenicity tests were conducted using detached leaf disc assays (1) and a P. cubensis isolate obtained from T. cucumerina. For this purpose, leaf discs were excised from 6- to 8-week-old leaves of T. cucumerina using a 20-mm cork borer. Five leaf discs were placed with their abaxial surface facing upward on moist filter paper in petri dishes. Each of four leaf discs was inoculated with four 10-μl droplets of a 1 × 105 per ml sporangial suspension, whereas the fifth disc was inoculated with water droplets and served as a control. Three replications were completed. The leaf discs were placed in darkness at 14 ± 2°C for 24 h and subsequently incubated with a 12-h photoperiod. After 10 days, sporulation was observed on the sporangia-inoculated leaf discs with similar morphological features to the initial field samples. To our knowledge, this is the first report of P. cubensis causing downy mildew of T. cucumerina in Malaysia. References: (1) A. Lebeda and M. P. Widrlechner. J. Plant Dis. Prot. 110:337, 2003. (2) J. Palti and Y. Cohen. Phytoparasitica 8:109, 1980. (3) H. Voglmayr and O. Constantinescu. Mycol. Res. 112:487, 2008.

Moreover, drought stress increases the amount of abscisic acid in the plant, which reduces the growth rate (Siebeneichler et al., 2020).Research has shown that chitosan consumption is common in living organisms, including plants (Ngo et al., 2015). Chitosan boosts plants' defenses and can even increase resistance to plant pathogens (Sharma et al., 2019). Chitosan is derived from chitin, which is an antitoxic substance. Especially in low doses, chitosan can improve a plant's resistance to pathogens by strengthening its immune system (Ngo et al., 2015). Chitosan protects cells against plant pathogens through lipid ARTICLE INFO

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