Effects of lodging of Echinochloa crus-galli L. on the herbicidal efficacy of MTB-951, a mycoherbicide using Drechslera monoceras (Drechsler) Subram. et Jain (= Exserohilum monoceras [Drechsler] Leonard et Suggs)

MTB-951 is a plant pathogen ( Drechslera monoceras ), which was isolated from native Echinochloa spp. in Japan. The conidia of this pathogen were used as the herbicidal active ingredient to control Echinochloa crus-galli L. The herbicidal efficacy of MTB-951 on E. crus-galli was drastically increased with an increasing water depth of between 1 and 10 cm. The efficacy also was increased when shoots were lodged by pushing down on them with a stainless steel net so that all parts of the weed were submerged. These results suggest that the contact area of the leaf surface of E. crus-galli with water is important for infection and that lodging the shoots of E. crus-galli might be effective in increasing the herbicidal efficacy. In order to find other methods to lodge the weed, we investigated several materials, of which diisononyl phthalate (DINP) was found to be the most effective. Using this material as a model, the effect of lodging on the herbicidal efficacy of MTB-951 was examined. The lodging ratio (ratio of the number of the plants lodged on the water surface to that of the total plants) was increased with an increased amount of DINP, between 0.5 and 8 kg ha⁻¹. The herbicidal efficacy of MTB-951 also was increased by DINP and a positive correlation was observed between the lodging ratio and herbicidal efficacy. These results indicate that lodging, which can increase the contact area between the leaf surface and water, enhances the herbicidal efficacy of MTB-951.     

Water velocity in artificial habitats of the Japanese crayfish Cambaroidesjaponicus

ABSTRACT:   The appropriate water velocity in artificial burrows for theJapanese crayfish species Cambaroides japonicus was studied.An experimental system of two artificial burrows (burrows A and B)of the same size was set in a large tank. The velocity of burrowA was 0 cm/s and that of burrow B was varied andset at 0 cm/s, 5 cm/s, 10 cm/s,20 cm/s and 30 cm/s. The selectionof these two burrows by C. japonicus was observed. No animalsselected burrow B significantly more than burrow A above 10 cm/s.At 20 cm/s, some crayfishes were swept away andcould not return to burrows because of the high water velocity.At 30 cm/s, most animals were swept away. We concludethat the appropriate water velocity for the suitability of artificialburrows and the immediate foraging area adjacent to the burrowsshould be as low as 5 cm/s.     

Effect of temperature on herbicidal properties of MTB-951, a mycoherbicide to control Echinochloa crus-galli L.

MTB-951 is a potential mycoherbicide using a fungal plant pathogen ( Drechslera monoceras ) isolated from native Echinochloa species in Japan. Conidia of this pathogen were used as the active ingredient and the effect of temperature on its properties was examined in a laboratory. The optimum temperature for conidium germination was broad between 15 and 35°C and no difference in the germination ratio existed within this temperature range. Mycelial growth was the fastest at 25°C but was slower outside of the range 15–35°C. When leaves of Echinochloa crus-galli L. were immersed in deionized water containing the conidia, cellular electrolyte leakage from the leaves was observed. However, no electrolyte leakage occurred from leaves of rice ( Oryza sativa L.) under the same conditions. The occurrence of electrolyte leakage from E. crus-galli was dependent on the temperature and was the highest at 25°C. Herbicidal activity of MTB-951 against E. crus-galli was high between 25°C and 30°C, but decreased at 35°C in a glass vessel. In the present study, it was revealed that the physiological and herbicidal properties of MTB-951 depended on the temperature.     

Effect of δ-aminolevulinic acid on the herbicidal efficacy of foliar-applied MTB-951, a mycoherbicide to control Echinochloa crus-galli L.

The conidia of a plant pathogen ( Drechslera monoceras [Drechsler] Subram. et Jain [=  Exserohilum monoceras [Drechsler] Leonard et Suggs]), MTB-951, which was isolated from native Echinochloa species in Japan, were used as the herbicidal active ingredient. The effects of δ-aminolevulinic acid (ALA) on the efficacy of foliar-applied MTB-951 on Echinochloa crus-galli L. were examined. First, foliar-applied MTB-951 exhibited almost no efficacy when no dew period was provided. However, the efficacy increased depending on the length of the dew period. MTB-951 and ALA exhibited an additive effect on E. crus-galli under 3 day dew conditions, although they exhibited a significant synergistic effect under no-dew conditions. When the leaves of E. crus-galli were immersed in deionized water containing the conidia of MTB-951, cellular electrolyte leakage from the leaves was observed. The ALA increased the electrolyte leakage by MTB-951 synergistically. Also, ALA increased the number of lesions on the leaves of E. crus-galli caused by MTB-951 under light conditions but failed to increase the number under dark conditions. These results suggest that ALA promotes infection with MTB-951 for E. crus-galli through its photodynamic action.     

有机水稻施用有机肥控制杂草技术的研究

本研究利用有机水稻栽培普遍施用的发酵鸡粪,采用不同使用时期和不同施用量的方法进行水田杂草控制试验。结果表明:发酵鸡粪能够有效控制杂草的发生;并且控制杂草效果,分施两次比一次性施用效果好;水稻产量也是施用两次比施用一次高。     

Influence of water management, application timing and temperature on efficacy of MTB-951, a mycoherbicide using Drechslera monoceras to control Echinochloa crus-galli L.

MTB-951 is a potential mycoherbicide using a fungal plant pathogen ( Drechslera monoceras ) isolated from native Echinochloa species in Japan. Conidia of this pathogen were used as the active ingredient and its herbicidal performance was examined in a greenhouse. The efficacy of MTB-951 on Echinochloa crus-galli L. was higher in deep water (7–9 cm) than in relatively shallow water (3–5 cm). In a postemergence application, the efficacy decreased as the leaf stage of E. crus-galli proceeded between the 1 and 2.5 leaf stage. For example, the control ratio (%) of E. crus-galli was 95% when applied at the 1 leaf stage, and 72% at the 2.5 leaf stage in 5 cm water. Generally, mycoherbicidal efficacy was less when applied pre-emergence rather than postemergence. Efficacy was also influenced by the duration of submergence in deep water. For example, when water depth was kept at 5 cm for more than 7 days after application and then decreased down to 3 cm, the efficacy was high. However, when the water depth was kept at 5 cm for less than 7 days, the efficacy was low. Efficacy was lower under high temperatures (35°C/25°C, day/night) than under low temperatures (25°C/15°C, day/night). Water management, application timing and temperature are important factors on herbicidal efficacy of MTB-951 to control E. crus-galli .     

Lethal limits of high temperature for two crayfishes, the native species Cambaroides japonicus and the alien species Pacifastacus leniusculus in Japan

ABSTRACT: Lethal limits of high temperature were studied to clarify the effects on the survival of the endangered Japanese crayfish species Cambaroides japonicus and the alien species Pacifastacus leniusculus . After the acclimation period for 2 weeks at 16°C, the temperature was raised at a rate of 1°C per week. As a result, the ultimate upper lethal temperatures of C.   japonicus and P.   leniusculus were 27.0 and 31.1°C, respectively, and the lethal temperature for P.   leniusculus was significantly higher than for C.   japonicus . The natural distributions of these two species are discussed in terms of the temperature tolerance.     

The aerobic bacterial flora of the middle and external ears in normal dogs

The aerobic bacterial flora of the middle and external ears was elucidated in 30 normal dogs (60 ears). Bacterial swab samples were obtained by rubbing the surface of the tympanic cavity and external ear canal. In the middle ear, bacteria were cultured from 48 per cent of the total ears and mainly included Escherichia coli (8 per cent), yeasts (8 per cent), staphylococci (7 per cent) and branhamella (7 per cent). In the external ear, bacteria were found in 46 per cent of the total ears and staphylococci (19 per cent) and yeasts (7 per cent) were the main isolates. Mycoplasma was found in one external ear sample, but in no middle ear samples in an examination of 20 ears. The same type of bacterium was hardly ever found in both the middle and external parts of each ear.