Disease Control and Plant Growth Promotion of \u3cem\u3e Miscanthus \u3c/em\u3e × \u3cem\u3e giganteus \u3c/em\u3e with \u3cem\u3e Trichoderma \u3c/em\u3e Bio-Inoculants

The second-generation bioenergy crop Miscanthus (Miscanthus × giganteus) is being assessed in New Zealand for its potential to provide shelter on irrigated dairy farms. Miscanthus is a perennial sterile hybrid vegetatively propagated rhizomatous C4 grass and the young rhizomes and roots are prone to infection by soil-borne fungal pathogens (Glynn et al., 2015) which can cause deleterious effects on plant establishment and growth. In Europe, several species of Fusarium such as F. avenaceum, F. culmorum, F. moniliforme and F. oxysporum have been implicated as causal agents of root and rhizome rot (Thinggaard, 1997; Covarelli et al., 2012) leading to poor field establishment of in-vitro propagated Miscanthus plants. When tested for their ability to cause disease of Miscanthus, Rhizoctonia solani (Kuhn) was reported as the most aggressive species among nineteen fungal pathogens of cereal crops (Glynn et al. 2015). In New Zealand, R. solani reduces seedling emergence and plant establishment of several herbage species and the problem may be alleviated through biocontrol using Trichoderma fungi (Kandula et al., 2015). In a glass-house study, the effect of four T. atroviride isolates on growth of tissue culture propagated Miscanthus plants in a soil naturally infested with R. solani was investigated

Enhancing seedling emergence and plant growth of forage brassica with a Trichoderma bio-inoculant

Forage brassicas occupy the largest area (250,000 ha) of cultivated crops in New Zealand (NZ) to supplement pastures both in the dairy and dryland farming systems. Forage yields are affected by poor crop establishment due to the increased susceptibility of brassica crops to Rhizoctonia solani, a soil-borne fungal pathogen causing damping-off and root rot. The effectiveness of a Trichoderma bio-inoculant (TBI) was evaluated in glasshouse experiments using potting-mix and field soils artificially inoculated with R. solani inoculum with kale variety "Gruner", forage rape variety "Interval" and turnip variety "Dynamo" as test crops. TBI treatment significantly increased seedling emergence of all the test crops. Regular monitoring of plant growth revealed that plants were healthier in the TBI treatment with lower incidence of wire-stem disease symptoms compared to controls. Increased seedling emergence resulted in sig­nificantly more shoot dry matter in the TBI treatment with kale and turnip plants, whereas the root dry matter was significantly higher in all the three forage brassicas tested. In the TBI treatment, visual observation of roots showed a marked increase in fine root growth in kale and forage rape plants, while in turnip, bulb growth was enhanced. On-going work is developing an appropriate seed-coating formulation that will allow TBI to be inte­grated into sustainable forage crop management prac­tices in NZ

Effect of Trichoderma bio-inoculant on emergence and growth of Camelina seedlings

Camelina (Camelina sativa) or false flax has been the subject of research in New Zealand as an alternative oilseed crop that can be used as renewable biodiesel feedstock. While being tested in agronomy trials, damping-off and root rot by Rhizoctonia solani was observed to constrain seedling establishment and seed-coating with fungicides was required. The effectiveness of a Trichoderma strain mixture applied in granule or prill formulation on two varieties of Camelina (Suneson and 4164) was evaluated in three glasshouse experiments. Soil from a field with known history of R. solani infestation was used. The bio-inoculant was applied either with or without fungicide (Vitaflo) coated seeds and the numbers of emerged seedlings, diseased and healthy plants were recorded. For the Suneson variety, application with either formulation increased seedling emergence compared with the bare seed control and seedling emergence with the granule formulation was equal to the fungicide treatment (p<0.05). For the 4164 variety, both bio-inoculant formulations increased seedling emergence significantly compared with the bare seed control. In the prill treatment for both Camelina varieties, shoot and root dry weights were equal to the fungicide treatment. With the granule formulation, root dry weight in both Camelina varieties as well as shoot dry weight in ‘4164’ gave significantly higher values than the fungicide treatment. When fungicide coated seeds were sown with the bio-inoculant formulations, significantly higher healthy seedling emergence was observed in Suneson but not 4164. The results from this study show that Trichoderma bio-inoculants can be used alone or in conjunction with a fungicide seed treatment to promote seedling emergence

Disease control and plant growth promotion of Miscanthus x giganteus with Trichoderma bio-inoculants

The second-generation bioenergy crop Miscanthus (Miscanthus × giganteus) is being assessed in New Zealand for its potential to provide shelter on irrigated dairy farms. Miscanthus is a perennial sterile hybrid vegetatively propagated rhizomatous C4 grass and the young rhizomes and roots are prone to infection by soil-borne fungal pathogens (Glynn et al., 2015) which can cause deleterious effects on plant establishment and growth. In Europe, several species of Fusarium such as F. avenaceum, F. culmorum, F. moniliforme and F. oxysporum have been implicated as causal agents of root and rhizome rot (Thinggaard, 1997; Covarelli et al., 2012) leading to poor field establishment of in-vitro propagated Miscanthus plants. When tested for their ability to cause disease of Miscanthus, Rhizoctonia solani (Kuhn) was reported as the most aggressive species among nineteen fungal pathogens of cereal crops (Glynn et al. 2015). In New Zealand, R. solani reduces seedling emergence and plant establishment of several herbage species and the problem may be alleviated through biocontrol using Trichoderma fungi (Kandula et al., 2015). In a glass-house study, the effect of four T. atroviride isolates on growth of tissue culture propagated Miscanthus plants in a soil naturally infested with R. solani was investigated

Development of a Trichoderma atroviride based bio-inoculant for New Zealand's pastures

New Zealand's pasture production is dominated by two species, perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.). The quality pastures they deliver are the key to New Zealand's NZ$22B pastoral production industries. However, New Zealand's pasture soils contain a diverse range of soil-borne pathogens that impact pasture yields. While controlling them remains a challenge, biological control may offer a solution. Following in-vitro and glass-house screening of Trichoderma isolates belonging to diverse species, a prototype pasture bio-inoculant (BPI) was developed from a mixture of four T. atroviride isolates. Field experiments over several seasons have produced variable responses to the PBI, ranging from nil in pastures grown in non-stress environments to highly significant increases in seedling emergence, plant persistence and dry matter production in pastures challenged by soil-borne pathogens and/or abiotic stress. Reasons for these results are discussed

Screening and identification of urease producing microorganisms from New Zealand pasture soils

Urea is the most commonly used fertiliser in agricultural systems because of its relatively low price, high nitrogen (N) content and wide availability. However, urea N can be quickly lost from the system via ammonia volatilization or nitrate leaching following urea hydrolysis by urease producing soil microorganisms (UPSMs). N availability to the plant is therefore reduced, and the production of nitrous oxide and leaching of soil nitrate would contribute to environmental damage. Soils from under dairy pastures across New Zealand were collected and UPSMs, including fungi and bacteria, isolated using ureacontaining medium and then identified using polymerase chain reaction (PCR)-based molecular methods. Fungal species identified included Absidia sp., Chaetomium sp., Cladosporium cladosporioides, Cordyceps sp., Fusarium culmorum, Fusarium graminearum, Fusarium oxysporum, Fusarium solani, Geomyces sp., Gliomastix murorum, Humicola grisea, Lewia infectoria, Mariannaea sp., Mucor hiemalis, Nectria sp., Paecilomyces carneus, Paecilomyces lilacinus, Paecilomyces marquandii, Penicillium spinulosum, Phoma exigua, Phoma paspali, Pochonia bulbillosa, Thelonectria veuillotiana (Cylindrocarpon candidulum) and Trichosporon sp., all of which have a role in urea degradation in soil. Pasture soil-resident urease producing bacteria were also identified as: Citrobacter freundii, Cupriavidus sp., Enterobacter ludwigii, Pseudomonas chlororaphis, Rahnella aquatilis, Serratia proteamaculans and Yersinia kristensenii. Cupriavidus sp. and Mucor hiemalis showed strong urease activity when cultured on urease medium. Biological suppression of UPSMs is being investigated as a method to reduce soil urease.Funding from AGMARDT (The Agricultural and Marketing Research Development Trust) for a postdoctoral fellowship is gratefully acknowledged

Trichoderma bio-inoculant formulations for enhanced seedling emergence, plant growth and seed yield of oilseed rape (Brassica napus L.)

In Canterbury, New Zealand, oilseed rape (Brassica napus L.) production can be constrained by soil-borne fungal diseases, viz., damping-off and root rot (Rhizoctonia solani) and stem-rot (Sclerotinia sclerotiorum). The ability of a Trichoderma bio-inoculant (TBI) applied in a granule or as a seed-coating formulation to control these pathogens was investigated in two spring sown field experiments at Lincoln (High disease pressure) and Oxford (low disease pressure). TBI granules and seed coat increased (P<0.05) seedling emergence by 38 and 35% at Lincoln and Oxford respectively. At the Lincoln site, both the formulations increased total dry matter and seed yield, the latter by 80%, primarily through a significant reduction in plants infected by S. sclerotiorum. At Oxford, the granule application increased total dry matter and seed yield, the latter by 40%, primarily through plant growth promotion. Seed oil content was significantly (P<0.05) increased at the Lincoln site but not at the Oxford site. The results indicate that the TBI has the potential to be a component of the crop management of oilseed rape in Canterbury

Increased bulb yield following seed coating of radish (Raphanus sativus L.) with selected isolates of Trichoderma species in soil naturally infested with Rhizoctonia solani

Red radish (Raphanus sativus) is highly susceptible to the soil-borne fungus Rhizoctonia solani, which can cause severe crop losses. In a glasshouse experiment, untreated seeds of radish cvs. French Breakfast and Red Round were grown in potting mix where R. solani inoculated wheat-bran was added at rates of 0.25, 0.5 and 1.0 g per 100 g potting mix. Seedling emergence was reduced by one third and two thirds respectively by the two higher inoculum rates, and final plant numbers were ca. 20%, 50% and 80% less than in the uninoculated control. The ability of Trichoderma spp. to increase radish yields by limiting the damage caused by R. solani has long been known but has not been evaluated in New Zealand. Inoculum of each of four Trichoderma spp. isolates LU132 (T. atroviride), LU785 (T. hamatum), LU1437 (T. harzianum) and LU1358 (T. polysporum) was prepared in sterile wheat-bran and 0.5 g wheat-bran was added per 100 g potting mix. In a second glasshouse experiment, R. solani (0.25 g inoculated wheat-bran) was added per 100 g potting mix before untreated seeds of both radish cultivars were sown. Potting mix without either R. solani or Trichoderma served as the control. Maximum seedling emergence did not differ among the treatments for cv. French Breakfast, but was increased by the presence of either isolate LU132 (T. atroviride) or LU1358 (T. polysporum) for cv. Red Round. The presence of isolate LU1347 (T. harzianum) in the potting mix significantly increased plant survival in both cultivars. Each of the four Trichoderma isolates reduced the percentage of diseased plants with isolate LU132 (T. atroviride) providing the strongest response. In a third glasshouse experiment, Trichoderma treated seeds, thiram fungicide treated and untreated seeds of both radish cultivars were sown in naturally R. solani infected soil. The same treatments were used in a field trial at a site known to be infected by R. solani. In the third glasshouse experiment, seed treatment with Trichoderma isolates LU1347 (T. harzianum), LU1358 (T. polysporum) and LU785 (T. hamatum) significantly increased bulb fresh weight in cv. Red Round, but no treatments increased bulb fresh weight in cv. French Breakfast. In the field experiment, bulb yield for the thiram seed treatment did not differ from that of the untreated control. However, seed treatment with isolate LU785 (T. hamatum) increased subsequent bulb yield by 96% for both cultivars, and seed treatment with isolate LU132 (T. atroviride) or isolate LU1358 (T. polysporum) also significantly increased bulb yield (by 85% and 60% respectively) in cv. French Breakfast. A possible explanation for this result was sought by undertaking a fourth glasshouse experiment for radish cv. Red Round only. In this experiment, all four Trichoderma spp. isolates more than doubled bulb yield by producing not only a greater number of bulbs but also larger bulbs than the untreated control. Trichoderma seed coating may provide an alternative to fungicide seed treatment for radish production

Biological control of pasture bare-patch disease with Trichoderma bio-inoculants

Pasture ‘bare-patch’, characterized by death of perennial ryegrass (Lolium perenne L) plants within six months of pasture renewal, was diagnosed as being caused by the soil-borne pathogens Gaeumannomyces graminis (severe root rotting) and Fusarium culmorum (crown rotting). Pasture swards were cut from the affected areas and used in a glass-house experiment to assess the ability of seven Trichoderma strains to control the pathogens. Using the inverted sward technique, the Trichoderma strains were applied to the soil in prill formulation (at a rate equivalent to 30kg/ha) and seeds of perennial ryegrass cv. Bealey were sown (100 seeds/pot). Seedling emergence, recorded 21 days after sowing (DAS), did not differ from the untreated control (range 86-92%) and there were no differences in shoot dry matter (SDM) when assessed at 44 and 84 DAS. However, by 158 DAS all seven Trichoderma treatments had a significantly increased SDM and at 218 DAS, SDM for three of the treatments was still over 40% greater than that of the control. Root dry matter (RDM) was also between 80-100% greater at 124 and 218 DAS for three of the Trichoderma treatments. The two strains of T. atroviride which significantly increased (P<0.05) both SDM and RDM also had the lowest root disease score for G. graminis. Whether this response can be obtained in the field is yet to be determined

Potential biological control of take-all disease in perennial ryegrass

Perennial ryegrass (Lolium perenne) is the major pasture grass in New Zealand but is highly susceptible to take-all disease, caused by the root-rot pathogen Gaeumannomyces graminis (Gg). Isolates of the fungus Trichoderma atroviride are known to control Gg but it is not known if a mixture of isolates would be more effective than individual ones. Soil from a field naturally infested with Gg was placed in containers in a glasshouse and sown with ryegrass seeds then treated with one of three Trichoderma atroviride isolates or a mixture of all three isolates. All T. atroviride treatments significantly increased shoot dry matter by 46–73% and root dry matter by 42–62% compared with the control but a mixture of isolates was no more effective than individual isolates. Application of T. atroviride also significantly decreased root disease severity, which was negatively correlated with root dry matter. Take-all in pastures could possibly be controlled by overdrilling grass with a single isolate of T. atroviride