Atsango Emmanuel Wesonga

The demand for cut flowers has risen in recent years, however, production of cut flowers face many challenges and the most important amongst the challenges are the environmental conditions and diseases that hinders production. Crown gall disease cause significant losses to rose production in Kenya. This study was undertaken to determine the effects of a mixture of amino oligosaccharins and alternaria activated proteins on the growth and quality of rose and incidence of crown gall disease on roses. The trial was arranged out in a Randomized Complete Block Design (RCBD) with four replications and five treatments comprising of three levels each of amino oligosaccharins and alternaria activated protein 0.5, 1, 1.5g/litre and copper based fungicide at the rate of 2ml/ litre along with control (water spray) in the greenhouse. Tissues with crown gall symptoms were collected from four different roses per treatment in the two sites, counted and the size determined and recorded fortnightly. Bacteria were isolated from eight different galls from four different plants. Representative colony types were identified via their growth on selective media (MacConkey agar) and on nutrient agar media were chosen from each gall sample and sub cultured by streaking on new media. Biochemical test of different isolates was done to identify the bacterial isolates. Data was collected on rose height, number of shoots, disease incidence and severity, flowering duration, stalk diameter, flower head diameter at cut stage and subjected to analysis of variance. Biochemical characteristics and colony types for the isolates were also determined. Application of amino oligosaccharins and alternaria activated protein at the rate of 1.5g/litre had significant (P≤0.05) effect on galling formation and reduced the numbers from 2.49 to 1.4 at the eighth week and 1.08 at the tenth week in Winchester while in Bahati, the number reduced from 1.54 to 1.03 ten weeks after treatment application. Significant differences in the treatments applied was observed, application of a mixture of amino oligosaccharins and alternaria activated protein at the rate of 1.5g/litre had significant (P≤0.05) effect on the number of shoots, plant height, flowering duration, stalk diameter as well as flower head diameter at cut stage.

Maximum number of shoots after six weeks (13.6 and 13.9) were recorded in plots treated with amino oligosaccharins at the rate of 1.5g/litre at Winchester farm (Nairobi) and Bahati farm (Nakuru) respectively. However, maximum height of 61.3cm and 59.6 cm were reported at Winchester and Bahati farms respectively after treatment with amino oligosaccharins at the rate of 1g/litre. Plants receiving amino oligosaccharins sprays at the rate of 1.5g per litre recorded significantly (P≤0.05) increased stalk length of 27.7cm at Winchester, and 29.6cm at Bahati and stalk diameter of 0.48cm at Winchester farm and 0.40cm at Bahati farm. Plants receiving amino oligosaccharins sprays at the rate of 1.5g per litre had shortened flowering duration of 19.2 days in Karen, 11.6 days in Bahati farm. The gram reaction indicated that the selected isolates were gram negative and were positive for catalase, motility, lactose, oxidase, salt tolerance and mannitol tests.

Exogenous applications of amino oligosaccharins and alternaria activated proteins in the greenhouse influenced positively the growth of roses and significantly decreased the number of galls, size and improved plant growth. The ability of the treatments to manage the disease can be attributed to enhanced defense mechanism attributable to amino oligosaccharins and alternaria fine proteins.

Key words: Agrobacterium tumefaciens, chitosan, proteins, roses, plasmids, plant defense