Field survey of Fusarium stem rot of lisianthus ( Eustoma grandiflorum) cultivated in Okinawa, Japan

Lisianthus ( Eustoma grandiflorum) has become a major flowering plant in Okinawa, the southernmost prefecture of Japan. Its cultivation area has increased steadily with each passing year for two decades. Simultaneously, many types of lisianthus diseases related to damping-off symptoms have also increased dramatically. To create a strategy for preventing the disease, disease symptoms and pathogenic organisms of primary problematic disease with seasonal variation in the emergence were investigated. The symptoms were diagnosed as Fusarium stem rot (Kukigusare-byo) and the pathogen of the disease was identified as Fusarium avenaceum based on multigene sequences analyses. Indeed, the PCR result of the isolated strain in this study was the same as that isolated from lisianthus plants with Fusarium stem rot in Hokkaido Prefecture. Furthermore, the pathogen is clustered separately from the other F. avenaceum strains isolated from lisianthus in the USA. Diseased lisianthus plants spread throughout greenhouses even though several fungicides were applied. Additionally, they appeared from November to January and increased to 0.3% of the total number. Fusarium stem rot was found in 43.8% of the total number of farms from 2020–2021 in Okinawa Main Island

Efficacy of a Simple Formulation Composed of Nematode-Trapping Fungi and Bidens pilosa var. radiata Scherff Aqueous Extracts (BPE) for Controlling the Southern Root-Knot Nematode

We tested a formulation composed of a mixture of Bidens pilosa var. radiata extract (BPE) and nematode-trapping fungi for its effects on Meloidogyne incognita. In earlier evaluations of the effects of plant extracts on the hyphal growth of 5 species of nematode-trapping fungi with different capture organs (traps), the growth of all species was slightly inhibited. However, an investigation on the number of capture organs and nematode-trapping rates revealed that Arthrobotrys dactyloides formed significantly more rings and nematode traps than those of the control. An evaluation of simple mixed formulations prepared using sodium alginate showed that nematodes were captured with all formulations tested. The simple mixed formulation showed a particularly high capture rate. Furthermore, in a pot test, although the effects of a single formulation made from the fungus or plant extract were acceptable, the efficacy of the simple mixed formulation against M. incognita root-knot formation was particularly high