DISEASE

NAME
Bacterial Rot
Various Bacterial Species


Description
Bacterial problem associated with water soaked strips on the leaves, stem, roots, fruit or flower. Bacterial wilts produce causative slime that clogs the water-conductive tissue of a plant.

Symptoms
Bacterial Blight(Pseudomonas mori) forms water soaked spots on the leaves and shoots, becoming sunken and turning black causing the leaves and twigs to wilt and die.
There is also a Bacterial Blight (Pseudomonas syringaepv pisi) that infects legumes during humid weather with water soaked spots on the leaves and stems near the base. The spots become dark and as the stem shrivels, yellow lesions appear. Leaves and fruit pods turn brown and die.

Bacterial Leaf Spot(Pseudomonas viburni) forms wet spots that enlarge becoming brown and sunken. These spots can be seen on the leaves and young stems and the bacteria overwinter in buds or in cankers. It is found on Viburnumspecies.

Bacterial Wilt(Xanthomonasspecies) infects palms causing the lower fronds to wilt then turn grey-brown and die. This is followed by the crown becoming spongy (rotted) attacking the vascular tissues and eventually causing the collapse of the crown. There is also a Bacterial Leaf Spot (Xanthomonasspecies) that causes spots on leaves with water-soaked margins and is found onAlocasiaspecies.

Bacterial Wilt


Bacterial Wilt(Pseudomonas solancearum biovar1 and 3). This disease initially turns the youngest leaves pail-green to yellow; they then wilt turn brown and die. It eventually affects the entire plant and is found on Heliconia species.


     Black Rot or Bacterial Wilt

Black Rotor Bacterial Wilt(Xanthomonas campestris) is a bacteria rot that infects the leaves and seedlings of Cruciferous vegetables causing 'V` shaped pale yellow blotches to appear, normally infection occurs along the margin of the leaf or through damaged areas of the leaf. It also causes the flower head to become stunted and the veins or water conducting tubes in the leaves and stems to turn brown or blackish. Heavy infections cause the plant to wilt and die.


Bud Rot(Xanthomonas cannae) infects young leaves and flower buds ofCannaspecies, killing them. Small whitish spots appear as the leaves or buds open, these enlarge then run together turning black. The symptoms also extend to the petioles and stems forming yellowish water soaked areas and the bacterium overwinters in the rhizomes.

Halo Blight of Beans(Pseudomonas syringaepv phaseolicola) forms water soaked or greasy angular spots on the pods or stems of the host. This causes the plants to yellow and become stunted. During humid weather a white slime is exuded from the damaged areas.

Soft Rot(Pecotbacterium carotovorum) affects bulbs, initially stops flowers from blooming or forming correctly. These flowers are shed, and the plant rots at the base causing it to collapse. On inspection of the bulbs a white foul smelling viscous smell is associated with a soft rot.

Wetwood(Erwinia nimipressuralis) causes wilting and branch dieback in Ulmusspecies. The wood forms dark water soaked areas with no obvious streaking in the outer sapwood.

Yellow Rot inIris

Yellow Rot(Xanthomonas hyacinthi)is a bacterial disease infects the cell walls of the leaf, stem and bulbs and caused yellowish water soaked areas to appear. These areas become brown and shrivel, or pockets of rot appear, soon engulfing the entire bulb. The disease may start from the leaf down or from the bulb up infecting the whole plant. A cross section reveals vascular tissue that is choked with yellowish slime. Infected plants soon brown off, collapse and die.

Source and Dispersal
The bacterium is found in infected plant material and not necessarily the soil and is spread by splashing water, wind or infected stock.

Favoured Conditions
It prefers warm moist conditions normally during spring.
     
Affected Plants
These bacteria attack many plants including; onions, Hyacinthspecies and its varieties, this can be a major problem in bulb nurseries.
Vegetablessuch as potatoes are also infected by blight which forms dark brownish spots on the leaves that become larger, eventually killing them and followed by lesions on the stems. The roots are infected by falling spores and peas suffer from a bacterial blight that forms spongy leaves with dark brown edges. The leaves and stem shrivel and die.

Strelitzia nicolai

Aglaonema species are a inflicted on by the Leaf Spot (Xanthomonas campestris pv. dieffenbachiae). This infection causes reddish-brown markings with bright yellow margins to appear along the edges of the leaves and under humid conditions water soaked spots appear, then enlarge into irregular shapes. Control methods include an using pathogen free stock when propagating and applications of copper sulphate to the foliage at the correct rate.

Archontophoenixand Strelitziaspecies are susceptible to the Bacterial Wilt(Pseudomonas solanacearum). The leaves become yellowish and brownish along the margins causes the fronds to wilt and dry out. The vascular tissue in the stems then becomes blackish and the plant dies prematurely.

Berberisspecies are infected by the Bacterial Leaf Spot(Pseudomonas berberidis) forming irregular dark green water soaked areas that turn purplish brown. It also infects young shoots and petioles or damaged areas.

Bougainvilleaand Limoniumspecies are infected by the Bacterial Leaf Spot(Pseudomonas andropogonis) which forms orange angular spots that are lighter in the centre and cause the leaves to fall prematurely. It is most common in tropical regions.

Caryota mitis(Clumping Fish Tail Palm) is infected by the Bacterial Blight(Pseudomonas avenea). The symptoms include water soaked translucent areas along the leaf veins that mature to brown then black with a chlorotic halo that is up to 2 mm wide by 50 mm long. Leaves of all ages are infected and immature leaves are more severely infected.
Control methods include eliminating overhead watering, removing infected foliage and improve air circulation around the plant.

Caryota mitis

Cheiranthusspecies and other plants in the Brassicaceaefamily are infected by the Bacterial Wilt(Xanthomonascampertris) causing the leaves to wilt, turn yellow and die. It also stunts the inflorescence and turns the phloem and xylem blackish. Other plants that are infected include, Arabis, Armoracia, Aubrieta, Brassica, Hesperis, Iberis, Lobulariaand Mathiolaspecies.

Corylus species are infected byBlight((Xanthomonas corylina) that attacks the leaves and branches.

Delphiniumspecies are infected by several leaf spots including the bacterial disease Black Leaf Spot(Pseudomonas delphinii) which produces irregular tar-like spots on the upper surface of the leaf with corresponding brownish areas on the underside. This infection may extent down the petiole to the twigs. It normally occurs during cool weather affecting the lower leaves first.

Dianthusspecies are infected by the Bacterial Wilt(Pseudomonas caryophylli) which turns the leaves greyish, then yellowish before dieing. Yellowish streaks are also seen on the stems.

Dieffenbachiaspecies are infected by two Bacterial Leaf Spots(Erwinia species) and (Xanthomonas campestrispv. dieffenbachiae). Both form yellowish spots that turn brown on the leaves that have water-soaked margins.

Eschscholtziaspecies are infected bt the Bacterial Blight(Xanthomonas papavericola) which forms tiny black spots that are water soaked and may be ringed.

Euphorbia pulcherrimais infected by Bacterial Canker(Corynebacterium poinsettiae) which forms streaks on the green stems that are water-soaked. The leaves may also be affected producing spots or blotches.

Gladiolus, CrocusandFreesiaspecies are susceptible to Bacterial Scab(Pseudomonas marginata). This disease attacks the corms by forming slightly raised yellowish lesions that develops a raised rim with a soft sunken centre, producing bacterial exudate. It also infects the leaves with small reddish spots appearing towards the lower part. These spots merge and destroy the basic cell structure (parenchyma tissue) in the petioles causing the leaves to fold downwards, eventually killing the plant.

Hedera helixis susceptible to the Bacterial Leaf Spotor Stem Canker(Xanthomonas hederae). This infection commences with pale green water soaked spots or areas appearing on the leaves. These areas than become brown-black and dry with reddish margins, eventually engulfing the leaf causing it to shrivel. The bacterium then extends along the twigs and into the stems causing cankers. Several Fungal leaf spots develop simular symptoms and may be difficult to distinguish the difference. Generally avoid high humid temperatures and water plants at the base.

     Hedera helix

Morusspecies are infected by Bacterial Blight (Pseudomonas mori).

Orchidssuch as Cattleya, Cymbidium, Cypripedium, Dendrobium, Epidendrum, Oncidium, Paphiopedilum, Phalaenopsis and Zygopetalumspecies are infected by Bacterial Brown Rot(Pseudomonas cattleya) which forms water-soaked leaf spots that turn brown. Phalaenopsisspecies are particularly susceptible.

Caryotaspecies are susceptible to Bacterial Leaf Blight (Pseudomonas albopercipitans). This disease forms elongated water soaked areas on the fronds that are translucent at first becoming blackish.

Roystonea regia,Cocos nuciferaand Phaseolus species are infected by Bacterial Wilt(Xanthomonasspecies).

Tropaeolumspecies are infected by Bacterial Leaf Spot(Pseudomonas aptata) forming spots and rotting the leaves. They are also infected by the Bacterial Wilt(Pseudomonas solanacearum) which gains access through damaged roots or through the stomates, causing yellowing, wilting and the death of the plant.

Zinniaspecies are attacked by Bacterial Wilt(Pseudomonas solanacearum).

Non-chemical Control
Remove and destroy any infected plants. As a preventive measure cultivate the surrounding soil to improve drainage, aeration and minimise weed growth. Do not over water and allow the soil surface to dry before rewatering. When handling the plants pick a dry period and take care to minimise damage.
At first sigh of infection the plant should be removed and disposed off and avoid replanting susceptible vegetables such as peas for up to three years.

Chemical Control
There is no satisfactory chemical control. It is important to take preventive measures.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.