TABLE 57 Various cases of gummy bark in sweet orange in southern Yemen

Classification of gummy bark variety Sweet orange variety Scion bark Stock bark Bud-union crease
Gum Pegs Pinholing Gain Pegs
• Sweet orange bark with mild to moderate gum impregnation • Rootstock is not Unrecorded affected (sour orange) + + - - - -
• No scaling of sweet orange bark • No bud-union crease Hamlin + + + - - -
• Rootstock is affected (rough lemon) Valencia late + + ++ +++ ++ +++
Hamlin + +   + + ++
Valencia late ++ + + + ++ +
• Bud-union crease Valencia late ++ +   + ++ ±
• Sweet orange bark with severe gum impregnation • Rootstock is not affected (sour orange) Washington navel ++++ ++ + - ± -
Hamlin +++ +   - ± -
Aboussoura navel +++ +   - - -
• Roughness or scaling of sweet orange bark • No bud-union crease Unrecorded +++ + +++ - - -
Washington navel ++++ + +++   - -

Key:
- no symptoms;
+ mild symptoms;
++ moderate symptoms;
+++ severe symptoms;
++++ very severe symptoms.

TABLE 58 Virus and virus-like diseases and fungal diseases in southern Yemen

Citrus areas and orchards

Psyllid vector of greening

Stubborn

Gummy bark of sweet orange

Cachexia of mandarin

Bark gumming of grapefruit (Kassala disease)

Psorosis young leaf symptoms

Concave gum

Scaly bark psorosis

Phytophthora gummosis

Rio Grande gummosis

Sphaeropsis knot

Boron toxicity
Mukayras area +++                      
Jawl Madrum area                 +++   +++  
Mudia-Lawdar area
Mudia nursery   + +++ +++   +++ ++   +++      
El Hayed orchard   + +++ +++   ++ ++ ++        
H. Al Khader orchard     +++     +++            
A. Ruwais orchard     +++                  
A. Rabbash orchard             +++          
M.S. Al Daker orchard     +++ +++         +++      
A. Hosein orchard     +++       +++   +++      
Lawdar nursery   + +++ +++ + +++ +++ + +++ +++    
Say'un-Tarim area
Snahuh orchard                       +++
Jaima farm   + +++     +++     +++      
Al Radod orchard   +++ +++                  
Quasr Al Qubba orchard       +++         +++      
Zinjibar-Gaar area
A. Mohson orchard     +++ +++                
Fourth Conf. orchard                 +++      

Key:
+ disease is of little importance;
++ disease is of moderate importance;
+++ disease is of great importance.