The survey also examined the level of existing knowledge about biological control and the willingness to implement such measures. POTENTIAL FOR GROWTH ENHANCEMENT WHEN ESTABLISHING COOL SEASON GRASS VARIETIES USING MODIFIED BIOLOGICAL CONTROLS.
INTRODUCTION
Disease control lists options ranging from the use of various fungicides to simple cultural practices. A reduction in disease symptoms in new growth may also be due to a reduction in disease inoculum in the straw layer (Cross, 1982).
Improved biological control efficacy of Trichoderma harzianum 1295-22 for foliar stages of turfgrass disease using spray application. Plant diseases. Bartholomew (ed.), Agricultural Production Guidelines for Natal: Rangelands in KwaZulu-Natal. KwaZulu-Natal Coordinated Extension Committee, Department of Agriculture and Environmental Affairs, Pietermaritzburg: South Africa.
AN OVERVIEW OF BIOLOGICAL CONTROL
INTRODUCTION
THE RHIZOSPHERE AND SUPPRESSIVE SOILS
- DISEASE CONTROL INDUCED BY BCAS
- PLANT GROWTH INDUCED BY BCAS
- Examples of plant growth promoting SeAs
- SCA APPLICATION
- INTEGRATED PEST MANAGEMENT (IPM)
Commercial application of mycoparasites provides protection against root diseases and can promote plant growth (Kim-Jeong et al., 1992; Kapulnik, 1996; Nebec, 1997; Harman, 2000). Chemical stimulation may also be required for the growth and expansion of hyphae in the soil (Knudsen et al., 1991).
MECHANISMS OF ACTION IMPLEMENTED BY BCAs
- PROPOSED MECHANISMS EMPLOYED BY BCAS FOR DISEASE SUPPRESSION
- PROPOSED MECHANISMS EMPLOYED TO INDUCE GROWTH RESPONSES
Trichoderma harzianum also has the ability to trigger a plant's natural defense mechanism (Yedidia et al., 1999). Niche exclusion and control of minor pathogens are proposed methods of antagonistic behavior (Windham et al., 1986).
ADVANTAGES AND liMITATIONS ASSOCIATED WITH BIOLOGICAL CONTROL
- ADVANTAGES OF BIOLOGICAL CONTROL
- LIMITATIONS OF BIOLOGICAL CONTROL
Realizing the importance of natural enemies in pest control will only encourage the use of SCAs. Once the potential problems and risks have been identified, there is little to worry about when issuing BCAs.
FUTURE OF BIOLOGICAL CONTROL
Weeds, insects, plant diseases and other plant constraints are increasing due to intensification of production systems (Thomas and Waage, 1996). As cropping or production areas increase, pests are "forced" to find alternative hosts that pose a threat to crops.
CONCLUSIONS
The demand for better varieties has also resulted in an increase in the movement of plant material and exotic pests and diseases into production areas.
Selection of bacterial antagonists for biological control of Rhizoctonia so/aniin rape (Brassica napus). Papavizas and R.J.Cook (eds).Biological control of plant diseases: progress and future challenges.
COMMON DISEASES ASSOCIATED WITH TURF AND PASTURE GRASSES
INTRODUCTION
Currently, the dominant method of controlling plant diseases is the use of agrochemicals. Only those diseases that were defined as serious or occasionally observed in the survey carried out in the area (see chapter 3) are mentioned. The diseases presented here have been summarized in a table identifying causative factors), common disease symptoms observed, disease cycle, common pastures and grass hosts, control measures and relative importance of the disease.
FUNGAL DISEASES OF TURF AND PASTURE GRASSES
Chemical control: is erratic as the fungal pathogen is often present deep in the soil. Resistance: must be combined with seed treatments for valuable efficacy in damping-off control.
PLANT PARASITIC NEMATODES AND THEIR EFFECT ON TURF AND PASTURE GRASSES
CONCLUSIONS
Selection of bacterial antagonists for the biological control of Rhizoctonia so/ani on oilseed rape (Brassica naptus). Chemical control of foliar diseases of perennial (Lolium perenne L.) and their effect on yield and quality. Ruddock. 1997. Effect of a single fungicide spray on yield and control of perennial ryegrass under an extended grazing regime.
Weeds, Pests and Diseases of Grasslands and Legumes. British Crop Protection Council, Croydon: United Kingdom. Nitrogen form and amount of nitrogen and chloride application for control of summer patch disease in Kentucky bluegrass.
ABSTRACT
INTRODUCTION
Due to increasing environmental concerns and increased resistance to pesticides, there has been renewed interest in the use of natural enemies (biological control) for disease control. A survey was compiled and sent to dairy/cattle farmers around Pietermaritzburg and farmers in the KwaZulu-Natal region to determine their management principles and identify pest problems and control measures implemented.
MATERIALS AND METHODS
- PASTURE PRODUCTION SURVEY
- TURF PRODUCTION SURVEY
- STATISTICAL ANALYSIS
- RESULTS OF THE PASTURE PRODUCTION SURVEY
- Fertilization and Iiming
- Grazing programs
- Weed management
- Insects and other pest management
- RESULTS OF THE TURF PRODUCTION SURVEY
- Greens base structure
- Turf grasses species
- Fertilization
Soil types encountered by the farmers are summarized in Figure 3.1. The majority of soil types recorded in the survey were deep red and heavy clay soils (each totaling approximately 30% of responses). About 52% of the farmers surveyed used urea (accounting for 15% of the total fertilizer used) as a N source, while limestone ammonium nitrate (LAN) (accounting for 12% of the total fertilizer used) was used by 42% of the farmers . Of the farmers surveyed, 91% indicated that they applied split dressings of N over an annual application.
Of the surveyed farmers, only 14 (25%) indicated that they use chemicals as a means of pest control. Regarding the potential of biological control, 61% of farmers surveyed indicated that they would consider implementing biocontrol.
Golf greens
Golf tees
Golf fairways
Understanding of biological control and proposed use
As this is a new concept to many, 31% of KwaZulu-Natal landowners surveyed indicated that they had little or no understanding of biological control.
RESULTS OF STATISTICAL ANALVSIS
- Turf production survey
The occurrence of kikuyu yellows was significantly reduced by both block and strip grazing (PsO.05). Increased incidence of pests, weevils (PsO.05), mealworms (PsO.1) and moles (PsO.1), were associated with the use of a bread and scrub camp. Significant weed control was also achieved with the use of Garlon (PsO.05) and physical weeding (PsO.1).
Common grass control was significant using MCPA (P~O.05) and chopper (PsO.1) which provided complete control. In terms of insect control using insecticides, the use of Karate has largely controlled bollworm (PsO.1), caterpillars (PsO.05) and catworm (P~O.1).
DISCUSSION
Of the P sources presented to farmers in the survey, 53% of the total responses recorded were attributed to diammonium phosphate. Nutgrass, which was identified as the major weed of the KwaZulu-Natal Midlands (Figure 3.6), was significantly (P~0.05) controlled by the use of MCPA, which is registered for the control of nutgrass. This can be attributed to the wet conditions, characteristic of the KwaZulu-Natal Midlands, which are ideal for insect pests.
The responses received in the grassland survey were lower than in the pasture survey. Individual responses received from the sports field and racecourse manager have little impact in terms of determining overall management and pest occurrence. 46% of farmers and ranchers in KwaZulu Natal received similar positive feedback on the implementation of biological control. The number of farmers and ranchers who understood the concept of biological control and were willing to implement such a measure was large (Tables 3.12 and 3.15).
Abbott (ed), Dairying in KwaZulu-NataI. KwaZulu-Natal Coordinated Extension Committee, KwaZulu-Natal Ministry of Agriculture, Pietermaritzburg: South Africa. A Guide to Plant Pest Control, 39thedition.National Department of Agriculture, Pretoria: South Africa. Temperate forages and their role in livestock farming: Agricultural Farmers Day 29 and 30 August 2001, Pietermaritzburg: South Africa.
Lawns: Basics, Construction and Maintenance of Fine Lawns, 3'd Edition. Thomson Publications, California: United States of America.
POTENTIAL FOR THE BIOLOGICAL CONTROL OF
HELMINTHOSPORIUM LEAF SPOT ON THE PANICOID GRASS USING AMENDED BIOCONTROL AGENTS
INTRODUCTION
The concept of biological control is becoming increasingly interesting as the antagonistic potentials of microorganisms are realized. Many chemical companies are now investing in the discovery and development of biological control agents (BCAs) (Froyd, 1997). The purpose of these experiments was to determine the potential of Bacillus sp. and Trichoderma harzianum Rifai to control Helminthosporium leaf spot, a common disease of Pennisetum clandestinum Chiov. kikuyu), kikuyu is a lawn and pasture grass used in the KwaZulu-Natal Midlands.
Biological control agents provide a safer alternative to the liberal use of fungicides for disease control. A further aim of the trial was to determine the taxonomy of the causative agent of Helminthosporium leaf spot in the KwaZulu-Natal Midlands.
MATERIALS AND METHODS
- SCANNING ELECTRON MICROSCOPY (SEM)
- IN VITRO TESTING
- Antagonism tests
- Koch's postulate
- FIELD TRIALS
Prior to the trial, the area received a lot of traffic as the camp provided a resting place for sheep requiring vaccinations. The stand was cut to 50 mm high and left for disease to re-establish (about three weeks). The experimental area was isolated from any animal traffic for the duration of the trial. The trial began on 1 March 2000 with an initial rating before the first application of treatments.
The experimental area was isolated from any animal traffic for the duration of the experiment. The trial started on 19 March 2002 with an initial assessment before the first application of treatments.
RESULTS
- SCANNING ELECTRON MICROSCOPY
- IN VITRO TESTING
- Antagonism tests
- Koch's postulate
From Table 4.3, a LSD(o.OSl=17.39) showed a significant difference (P-o:;O.05) between the zero dose treatment of PUNCH XTRA and the full dose rate only. REML analysis of the calculated mean represents a single value for the controls of all treatment types (Table 4.5). Significant differences were noted in terms of FD% where at a LSD(o.OSl == 17.86 PUNCH XTRA and the control differed significantly and at LSD(O.OSl= = 15.36BIOSTART and PUNCH XTRA differed significantly Based on LSD values shown in Table 4.5 for the treatment type doses for FD%, the control treatment differed significantly from the half dose of ROOTSHIELD and from the full dose rate of PUNCH XTRA.
From Table 4.8, the control treatments of PUNCH XTRA and BIOSTART accounted for the lowest wet weight but the highest dry weight and dry matter percentage. Analysis of variance showed a significant difference (P.,O.05) between the mean of treated and untreated plots (Table 4.12).
16 -14 'ifl
DISCUSSION
The differences in disease control between treated and untreated plots were found to be significant only for the 2000 study. Treatment doses in both studies, with the exception of the full dose of Trichoderma kd for the 2002 study, resulted in a reduction in disease. There are a number of factors that may be responsible for the inconsistent results and non-significant differences observed across studies.
Variation in results obtained between the two trials can be attributed not only to the different treatment used but also to the fact that FD% indicated a higher disease pressure for the 2000 trial. Increased disease incidence for the 2000 trial may have been associated with the higher rainfall received during February to April (mm difference between trials).
1994. Plant growth enhancement and disease control by Trichoderma harzianum in vegetable seedlings grown under commercial conditions. European Journal of Plant Pathology. Eshel and U.Kafkafi (eds.), Plant Roots: The Hidden Half, 2nd ed. Marcel Dekker, New York: United States of America. A formulation of Trichoderma and Glioc/adium to reduce Rhiioctonia so/ani-induced damping off and saprophytic growth of the pathogen in a soilless mixture.
POTENTIAL FOR GROWTH STIMULATION IN THE ESTABLISHMENT OF COOL SEASON TURFGRASS VARIETIES USING AMENDED
BIOCONTROL AGENTS
INTRODUCTION
Over the years, this has led to a renewed interest in biological control, with several studies on disease control and growth stimulation based on antagonistic microorganisms. It is believed that antagonistic microbes colonize the rhizosphere after inoculation and form a close relationship with the plant roots (Schroth and Becker, 1990). The aim of these studies was to determine the growth stimulation potential of experimental formulations of antagonistic microbes on grass species, both in vitro and in vivo.
It has been suggested that growth stimulation may be due to colonization of the plant rhizosphere by antagonists, resulting in increased moisture and nutrient uptake by the plant (Cook, 1990). Antagonistic colonization of the rhizosphere also potentially protects against soil-borne pathogens that would reduce plant growth potential (Harman, 2000). The method and rate of microbial application plays a key role in the establishment and maintenance of a corrected antagonistic population (Fravel, 1992). Too large an Iowa population would not stimulate growth, while too high a population would exceed the carrying capacity of the rhizosphere (Papavizas). , 1985; Handelsman and Stabb, 1996).
MATERIALS AND METHODS
- IN VITRO POT TRIAL Trial site
