Lab 4

It is the abnormal increase in cell division giving rise to galls

An abnormal increase in cell size

• Caused by agrobacterium tumefaciens
• Mostly effect woody, perennial hosts, tree fruits and grapes
• Grasses are only plant to escape this disease
• Once infection occurs growth of the galls are independent of the bacterium

• Galls
• Disrupts nutrient and water flow

Systemic infection of agrobacterium tumefaciens occurs when individual cells break off the gall and travel through the vascular tissue to other parts of the plant

• Rotation with non-host crop
• Avoid wounding of Plant and control root chewing insects
• Use disease free plants
• Active galls can be killed using bacticin
• A biological control agent called agrocin84 ( contains A. Radiobacter strainK84 dip rootstocks)

• Caused by dibotryon morbosum
• Infects prunus species
• Disease is limited to North America
• Swellings on twigs and branches

• Foliar application of fungicide in the spring
• Removal and destruction of galls
• Removal of native or weedy hosts near orchards

• Disintegration of host tissues are a result of enzymatic activity of pathogen
• Most common enzyme are cellulases which degrade cellulose
• Pectinases which degrade pectin

• It makes ascospores in a pseudothecium
• The pseudothecia are embedded in a dark colored mass of fungal tissue called stroma

• Rain for the release of ascospores
• Temps 13-25C

Watery disintegration of plant tissue followed by slimy masses and odors

Are bacteria that infect and colonize plant tissue and in the process release extra cellular enzymes that degrade the plant tissue

• Infection by pectobacterium carotovorum
• Occurs in the field and post harvest
• Affects primarily vegetables

• In crop:
• Avoid root wounding
• Start with healthy seed
• Post harvest:
• Sanitation
• Cold storage

Bacteria that have a thick peptidoglcan and retain the crystal violet stain

They have an outer membrane with a thin peptidoglcan layer

Fungi that colonize dead tissue

Is a wood decay disease characterized by the whitish color of the decayed wood that results from the removal of lignin

The decayed wood is a brownish color due to the removal of cellulose from the wood by the fungus.