THE PATHOGENICITY AND TOXIGENIC PROPERTIES OF Fusarium crookwellense L.W. Burgess, P.E. Nelson & Toussoun DEPENDING ON WEATHER CONDITIONS

Field inoculation experiments were performed during 2015–2017, in south-eastern part of Poland. The pathogenicity of F. crookwellense was estimated based on the kernels yield reduction of 10 selected oat genotypes. Panicles of oat were inoculated with conidial suspension of F. crookwellense strain No. 72 which caused a reduction in kernels yield by 28.54% and kernels number per panicle by 28.07%, compared to the control. The lowest yield reduction, as a result of the panicle inoculation with F. crookwellense, was found in the case of the cultivar ‘Pablo’ (18.73%), while the highest in the case of breeding line POB 961-1344/13 (36.4%) and cv. ‘Kozak’ (34.3%). Statistically the highest average yield reduction was observed in year 2016, when a higher amount of rainfall, especially in July (just after inoculation) and higher temperature, compared to the long-term standard, were observed. During the period between inoculation and harvest, F. crookwellense was able to produce nivalenol, fusarenone X and zearalenone in oat kernels at the average level of 0.065 mg∙kg-1, 0.026 mg∙kg-1 and 0.015 mg∙kg-1 respectively.

Occurrence of Fusarium crookwellense in Poland

Paper presents the occurrence of th new spocies <i>Fusarium crookwellense</i> on cereals and potato tubers in Poland in 1985-1986.

The occurrence of Fusarium culmorum (W. G. Sm.)Sacc., Fusarium avenaceum (Fr.) Sacc. and Fusarium crookwellense Burgess, Nelson & Toussoun on oats lines (Avena sativa L.)

Investigations were carried out in 1996-1998 in the experimental fields in Zamość region. The following ten lines of oats were tested: CHD 894, CHD 1095, CHD 1236, CHD 1607, CHD 1653, CHD 1692, STH 2293, STH 2393, STH 2494, STH 2694. The seedlings which showed symptoms of either root and sheath nectosis, or rotting stems ranged form 9-36 ad 9-70% of all seedlings tested, respectively. Results of mycological analysis of seedlings showed that <i>F.avenaceum</i> and <i>F.culmorum</i> were most frequently represented on infected parts (43% ad 42% of all <i>Fusarium</i> spp. isolates respectively), and also they were the most frequently obtained from stems with necrotic stripes (24% and 46% of all <i>Fusarium</i> spp., respectively). Apart from <i>F.avenaceum</i> and <i>F.culmorum</i> there was some <i>F.crookwellense</i> found every year on lower internodes.

Molecular Phylogenetic Analysis, Trichothecene Chemotype Patterns, and Variation in Aggressiveness of Fusarium Isolates Causing Head Blight in Wheat

Certain Fusarium species cause Fusarium head blight (FHB) in wheat and other small grains. Differences in characteristics of the pathogen species/isolates used in breeding programs may affect reaction of host genotypes, leading to erroneous results. To clarify differences among Fusarium isolates from different geographical zones, the phylogenetic, chemotypic, and pathogenic abilities of 58 isolates collected from three wheat-producing countries (Canada, Mexico, and Iran) were investigated. Phylogenetic relationships among the isolates were characterized using the Tri101 gene sequence. All Canadian and Iranian isolates clustered in one group and were identified as F. graminearum lineage 7 (=F. graminearum sensu stricto) within the F. graminearum (Fg) clade. The isolates from Mexico were identified as either F. graminearum lineage 3 (=Fusarium boothii) within the Fg clade or Fusarium crookwellense. A polymerase chain reaction assay based on the Tri12 gene identified three trichothecene chemotypes of 15-ADON, 3- ADON, and NIV, with 15-ADON being the most common. All F. boothii isolates from Mexico were of the 15-ADON chemotype, while all F. crookwellense isolates were determined to be NIV producers. While we did not find the NIV chemotype among the Canadian isolates, 25.6% of the Iranian isolates were determined to be NIV producers. High level of variation in aggressiveness was also observed among and within the species tested: F. graminearum sensu stricto isolates were the most aggressive, followed by those of F. boothii, and lastly by F. crookwellense. The differences observed among the isolates may explain why wheat lines/cultivars demonstrate different reactions to FHB in different geographical zones.

Fusarium head blight of winter rye (Secale cereale L.)

Investigations on <i>Fusarium</i> head blight of rye were carried out in the years 2005-2007 on 10 production fields in the Lublin region. The percentage of heads showing the fusariosis symptoms in the years 2005-2007 ranged from 0 to 7%. Mycological analysis of kernels and chaff obtained from heads with <i>Fusarium</i> blight (scab) symptoms showed that <i>Fusarium avenaceum</i>, <i>Fusarium culmorum</i> and <i>Fusarium sporotrichioides</i> were the largest threat to heads of this cereal. The species of <i>Fusarium poae</i> and <i>Fusarium crookwellense</i> were also isolated from infected rye heads. The dominance of particular species in infecting rye heads was determined by weather conditions.

First Report of Fusarium crookwellense Causing Tip Blight on Cones of Hop

Hop (Humulus lupulus L.) is grown primarily for the alpha and beta acids produced in the strobile (cone) and used for bittering beer. In late summer (March) 2001, necrotic lesions covering the tips of cones of cvs. Agate, Nugget, and Willamette at hop farms in Tasmania, Australia, were observed. The necrotic lesions encompassed the proximal tips and affected between 5 and 60% of the cone; however, all bracts in the whorl were always affected. Diseased cones were observed in all seven gardens included in the survey. The incidence of plants with cone tip blight in ‘Nugget’ ranged from 5 to 30% in three gardens, in ‘Agate’ ranged from 3 to 10% in three gardens, and in the only ‘Willamette’ garden 30% of cones were affected. Pieces of infected hop cones (N = 55) were surface-treated for 1 min in 2% sodium hypochlorite, placed on 2% water agar, and incubated at 22 ± 2°C. Fusarium crookwellense Burgess, Nelson, & Toussoun was isolated from 95% of the cones (1). F. crookwellense was identified on carnation leaf agar by L. Burgess, University of Sydney, Australia. Koch's postulates were fulfilled by inoculating detached mature hop cones of cvs. Nugget and Willamette (N = 20 for each cultivar) with an atomized conidial suspension (3.5 × 105 spores of a single F. crookwellense isolate per milliliter) until runoff and incubated at 20 ± 2°C in a sealed container on plastic mesh over tissue wetted with sterile distilled water. Symptoms first appeared 5 days after inoculation and were identical to those found in the field. No disease symptoms were observed on cones subjected only to sterile distilled water. The pathogen was reisolated from diseased tissue on inoculated cones, completing Koch's postulates. Similar disease symptoms on hop cones have been described in Oregon and were associated with infection by F. sambucinum and F. avenaceum (C. Ocamb, personal communication). To our knowledge, this is the first report of the infection of hop cones by F. crookwellense. Reference: (1) L. W. Burgess et al. Laboratory Manual for Fusarium Research, 3rd ed. University of Sydney, Australia, 1994.

Fungal Infection and Presence of Deoxynivalenol and Zearalenone in Cereals Grown in The Netherlands

In 1991 and 1993 cereals were sampled during harvest in The Netherlands. The samples were tested for the presence of molds and the samples of 1993 were additionally tested for the mycotoxins deoxynivalenol and zearalenone. The molds were identified to genus level and those belonging to the genus Fusarium to species level. The total fungal infection of cereals in 1991 did not differ from 1993, with a median value of 5.0 log CFU g−1 in both years. The incidences of the genera Aspergillus, Penicillium, the group of Mucor and Rhizopus, Cladosporium, and Fusarium differed considerably between the two years, possibly caused by the different weather conditions. The numbers of samples infected with Fusarium were much higher in 1993 (83%) than in 1991 (34%). In 1991, no Fusarium was detected in samples from the southern part of The Netherlands, as opposed to 1993, when Fusarium was found in all regions sampled. The most dominant Fusarium species in 1991 were Fusarium culmorum and Fusarium avenaceum. In 1993, Fusarium poae, Fusarium culmorum, and Fusarium crookwellense dominated. All these Fusarium species are known mycotoxin producers. Three percent of the cereal samples of 1993 contained deoxynivalenol and 1% contained zearalenone in levels of over 500 μg kg−1 and 200 μg kg−1, respectively. This study has shown that the incidences of various fungal genera and Fusarium species in cereals in The Netherlands can vary from year to year. Considerable numbers of toxigenic Fusarium molds can occur and Fusarium mycotoxins may be present.