The document discusses several diseases that affect pomelo trees, including Tristeza, Citrus Scab, Citrus Canker, Anthracnose, Citrus greening, Phytophthora gummosis, Citrus Chlorotic dwarf virus, and Pseudocercospora Fruit and Leaf Spot. Citrus Canker is a serious bacterial disease that reduces fruit growth and causes leaves and fruit to drop prematurely. Citrus greening causes mottling and yellowing across leaf veins. Phytophthora gummosis commonly causes dark exudate from tree bark.
13. Citrus Canker
• Citrus canker is a serious bacterial disease of citrus trees including grapefruit,
lemons, limes and oranges. It reduces the growth of new fruit and spoils healthy
fruit. Outbreaks of this disease have been eradicated from Queensland and the
Northern Territory at great cost to industry and growers.
• The disease attacks the leaves, twigs and fruit of citrus trees. It causes the leaves
to drop and fruit to fall to the ground before it ripens. People may also contribute
to disease spread by moving infected plants or plant parts
22. Citrus greening
Identification tip:
• Mottling and yellowing that
cross leaf veins help to
distinguish citrus greening
(Huanglongbing), an exotic
tree-killing bacterium.
When zinc deficiency is the
cause, discoloring occurs
between distinctly greener
veins. Report to agricultural
officials any finding citrus
greening disease
26. Phytophthora gummosis
Identification tip
• :Phytophthora gummosis is
the most common cause of
profuse dark exudate from
bark. Several other limb,
trunk, and root diseases
cause oozing bark and can
stunt and sometimes kill
trees.