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Fusarium solani Mart. (Sacc.) is the causal agent of stem rot and damping-off of lisianthus (Eustoma grandiflorum (Raf.) Shinn.) (1). Since the end of the 1980s, when this flower crop was introduced in Argentina, it has been affected by a basal stem rot (2). A previously undescribed disease was observed in 100% of the greenhouses in the Buenos Aires Province that grow lisianthus. Symptoms that developed after seedlings were transplanted included stunting, shortened internodes with reduced stem diameter, and small narrow leaves that were a dull green color. Some affected plants turned yellow-brownish and died 2 to 3 months after transplanting. Other plants recovered but produced low quality flowers later than normal. A third group of plants remained stunted (5 to 10 cm high) until the last flower harvest (about 8 to 10 months). F. solani was consistently isolated from basal stems and roots of diseased plants. For pathogenicity tests, inoculum was produced by culturing the fungus for 10 days in petri dishes containing sterile moistened rice. Inoculum was air dried, crushed, and mixed with soil that had been autoclaved at 112°C for 40 min on each of two consecutive days. The propagules in the soil were estimated by soil plate dilutions on the Nash & Snyder-PCNB medium at a ratio of about 104 CFU/g soil. Twenty plants of each cultivar Echo White and Echo Blue, whose roots had been pruned, were planted in both infested and noninfested soil. After about 40 days, stunting was observed in 85% of the inoculated plants, while controls remained asymptomatic. F. solani was reisolated from symptomatic plants, thus fulfilling Koch's postulates. A test also was conducted in a commercial greenhouse that produced lisianthus for several years, in which healthy plants were planted in three plots fumigated with methyl bromide and in three nonfumigated plots. The mean cfu/g soil of F. solani in the methyl-bromide treated plots was 5 × 102 and 1.6 × 104 CFU/g in the nontreated plot. After 120 days, the incidence of stunting in the treated plots was 0.6 and about 88% in the control plots. F. solani was recovered from symptomatic plants. Because disinfestation of soil is generally practiced in flower production, stunted plants are limited and can be confused with root problems. This is the first report of F. solani causing stunt on lisianthus. References: (1) J. J. Taubenhaus and W. N. Ezekiel. Phytopathology 24:19, 1934. (2) S. M. Wolcan and G. A. Lori. Invest. Agr. Prot. Veg. 11:465, 1996.

Since 1995 severe losses were recorded on the production of Chamelaucium uncinatum in the vicinity of La Plata. In 2010, with the aim to confirm the identity of the causal agent of Geraldton waxplant basal rot, molecular studies were added to the morphological observations of the pathogen. P. nicotianae was identified as the causal agent of the disease.

Passion fruit (Passiflora edulis Sims.) is a subtropical fruit recently cultivated in Misiones Province, Argentina. In spring 1997, a severe epidemic of anthracnose was observed. Disease incidence was ≍95%, causing high yield losses. Sunken, gray lesions on the whole surface of young fruits were observed. Under humid conditions, acervuli containing masses of spores and dark setae were found within lesions. On leaves, tendrils, and twigs, circular and irregular brown spots with darker edges were observed. Abortion of flowers also was recorded. Cultures on potato dextrose agar yielded abundant, gray aerial mycelium and one-celled, hyaline, oblong conidia with obtuse or rounded ends (11.2 to 15.0 × 3.8 to 4.6 μm). Perithecia were scarce (90.2 to 220.0 μm). Asci were not conspicuous, and ascospores measured 10.8 to 23.4 × 3.5 to 7.0 μm. Based on morphological characteristics, the fungus was identified as Glomerella cingulata (anamorph Colletotrichum gloeosporioides) (2). Fruits and leaves of P. edulis with and without wounds were sprayed with a conidial suspension (106/ml) and incubated in plastic bags for 48 h. Lesions similar to original symptoms were observed after 2 weeks only on wounded leaves and fruits. G. cingulata was reisolated, confirming Koch's postulates. This disease has been recorded in Brazil and Japan (1). This is the first report of G. cingulata on passion fruit in Argentina. Reference: (1) E. Francisco Neto et al. Summa Phytopathol. 21:25, 1995. (2) J. A. von Arx. Phytopathol. Z. 29:413, 1957.