This document summarizes several diseases that affect grapefruit, including the symptoms and causes. It discusses citrus canker caused by the bacterium Xanthomonas axonopodis, which presents as raised lesions on leaves and fruits. It also outlines stubborn disease caused by Spiroplasma citri bacteria, which stunts trees and produces misshapen fruits. Finally, it provides information on blast caused by Pseudomonas syringae bacteria, which causes leaf and twig lesions.

2. Grape Fruit Diseases
A
Lecture To ToT trainees ( FFS)
By
Mr. Allah Dad Khan
Provincial Coordinator IPM KPK
MINFAL Pakistan

3. Citrus canker
Xanthomonas axonopodis
Symptoms
Citrus canker on
grapefruit
 Raised lesions on leaves,
often at leaf margin or tip;
lesions may also be
present on twigs and
fruits; young lesions are
usually surrounded by
yellow halo; depressed
brown craters formed from
collapse of lesions
 Cause
 Bacterium

15. Stubborn disease
Spiroplasma citri
 Symptoms
 Stunted trees; leaves
shorter and broader,
cupped and upright;
may be chlorotic or
have a mottled
appearance; stunted,
malformed fruits and
low yield
 Cause
 Bacterium

16. Blast
Pseudomonas syringae
 Symptoms
 Water-soaked or black
lesions on leaf
petioles;which rapidly
expand along the leif midrib;
cankers on twigs and
branches; twigs may be
girdles and die; leaves
turning black and dying;
black lesions may be
present on fruit
 Cause
 Bacterium

17. Anthracnose
Colletotrichum gloeosporioides
Anthracnose symptoms on
grapefruit
 Symptoms
 Dieback of twigs;
premature leaf drop;
dark staining on fruit;
leaves and twigs
covered in dark spores
 Cause
 Fungus

18. Brown rot
Phytophthora spp
 Symptoms
 Water-soaked lesions
on fruit close to
maturation; leather tan
to dark brown lesions
on fruit; lesions with a
pungent smell; leaves,
twigs and flowers may
be turning brown
 Cause
 Oomycete

30. Tristeza disease
Citrus tristeza virus (CTV)
Pits in trunk of grapefruit tree
infected with tristeza disease
 Symptoms
 Light green foliage; poor
new growth; leaves may be
dropping from tree; young
trees blooming early;
severely infected trees are
stunted and bushy in
appearance with chlorotic
leaves and brittle twigs;
some strains of the virus
cause elongated pits in the
trunk and branches which
give the wood a rope-like
appearance
 Cause

34. Huanglongbing (Citrus greening, Yellow dragon
disease)
Symptoms of huanglongbing
on grapefruit leaves
 Symptoms
 Yellowing of one limb or
one area of canopy;
yellowing of leaf veins;
blotchy mottling on leaf
blades; twig and limb
dieback; fruits dropping
prematurely; small
upwardly pointing leaves;
small, misshapen fruit;
fruit very bitter
 Cause
 Bacteria
 Candidatus Liberibacter asiativus
Candidatus Liberibacter africanus
Candidatus Liberibacter americanus