1. Magdalene Wanza and Dr. Maina Mwangi
Department of Agricultural Science and technology, Kenyatta University, P. O Box , Nairobi, Kenya.
MANAGEMENT OF CROWN GALL DISEASE IN THE PRODUCTION OF FLOWER CUTTINGS IN KENYA    
2nd Phytosanitary conference ,KEPHIS headquarters, Nairobi
4th-8th June,2018.

2. Introduction
Horticulture sub-sector is one of the top foreign exchange earners.
The growth rate averages 15-20% per annum (FPEAK, 2015).
Flowers accounted for 69.8% of the value of horticulture exports (KNBS,2017).
Flowers produced in Kenya are marketed as Cut flowers, e.g roses or flower cuttings mainly in Europe.
Flower cuttings constitute a variety of different flowers:
-Chrysanthemum
-Argyranthemums
- Leucanthemums
- Poinsettias
- Pelargoniums

3. Crown gall disease
Plant Diseases are among the serious challenges to the agricultural sector in Kenya.
Crown gall is caused by Agrobacterium tumefaciens.
It is the most widely distributed bacterial disease of plants in the world (Hudelson and Joy,2005).
It affects more than 100 species of fruit crops, woody and herbaceous ornamentals.
Induces galls, reduces yield, destroys vascular tissues, causes dieback or plant death.
It reduces the marketability of nursery stock (Deacon, 2015).
In Kenya, it is a major threat to roses, Chrysanthemums, Argyranthemums, Leucanthemums etc
Crown gall was introduced in 1998 through infected rose root stock from Israel.
Currently it is widely spread in nurseries, commercial production areas and in uncultivated fields

4. Infected plants Rose flower plant showing chlorotic symptoms
Infected mother plants for production of flower cuttings

5. More infected plants

6. Management of crown gall
Producers have tried various management strategies against the disease (KFC,2011).
Prevention of inoculum introduction,
Use of nursery stock free of galls near the crown,
Sterilization of propagation substrate with chemicals, heat or antibiotics (KEPHIS, 2017).
Use of bio-pesticide based products such as neem oil that have temporarily managed Crown gall(Kado, 2002).
Use of AB spray composed of vegetable soap, essential oils and fermented plant extracts has been used for coating and drying galls in roses (Kado, 2002).

7. Cont.
Biological control has been tried with Agrobacterium radiobacter (Farrand, 1990).
Copper based compounds have been used with temporal effect (Judith,2010).
Dipping of seedlings in a bactericide at transplanting, e.g.
Use of Creosote-based compounds
strong oxidants such as Sodium hypochlorite is ineffective (Burr,2004).
Antibiotics and Copper bactericides can kill the bacterium on contact,
…but they do not penetrate plant tissues to come into contact with bacteria residing endophytically (Burr, 2004).

8. Challenge
Crown gall remains a major challenge in East Africa (Maina et al, 2011).
Limited research done on effectiveness of various management strategies.
Chemicals largely avoided due to health and environmental concerns
health risks resulting from occupational exposure
residues on food
Pollution of drinking water (Damalas and Ilias, 2011).
Better management strategy with less pesticides use needed.

9. Ongoing research
Electro-chemical activated water, commonly abbreviated as ECA water
ECA is a concentrated solution that has many disinfecting properties
Ozone, chlorine, hypochlorous acid and other biocidal agents that kill crop pathogens
ECA water is harmless to the environment
Proven wide target range: bacteria, root and fungal diseases, viruses and biofilm.
Rheum officinale composed bio-pesticide that manages fungal and bacterial diseases
Foliar application solution containing colloidal copper.
Copper oxychloride contains 50% metallic Copper. Mode of action is contact.
Vegetable oil. Manages agrobacterium by suffocation.

10. THANK YOU