Panama Wilt

• Panama wilt, also known as Panama disease or Fusarium wilt of banana (Fusarium oxysporum), is a destructive wilting disease of bananas. According to the University of Hawaii extension service, one group of bananas, the Bluefields, is no longer extensively grown in Hawaii thanks to Panama wilt. Growers developed the Cavendish group of varieties, which show some resistance, but even these are now threatened. The infection comes in through the banana plant's root system and progresses to the rhizome. At this point, brown streaks or flecks become visible on the leaves, which yellow, split and then wilt. Eventually, all leaves die and the tree dies. There is currently no effective control for this disease.
  
  

Banana Bunchy Top Virus

• When a banana plant is attacked by the banana aphid, Pentalonia nigronervosa, the plant is laid open to infection from banana bunchy top virus. You can identify this disease by studying its symptoms, or send samples in for laboratory analysis. Your first line of defense is to control the aphids by spraying. Prevention of the virus is key; you must destroy all parts of infected plants, monitor the bananas for infection and ensure plants are healthy before planting them. In an affected tree, the leaves bunch together instead of spreading out. Mottled marks appear on the leaf stems and the leaves themselves gain small dark dots. Ultimately, the fruit is stunted and does not properly develop.
  
  

Black Leaf Streak

• Black leaf stream (Mycosphaerella fijiensis) is a fungus-borne disease of the banana. During wet, winter weather, up to 30 percent of a plantation can succumb if the infection takes hold. Fortunately for growers, approved fungicides offer good control, though they also cause unsightly spots on the fruit. Cover the fruit with plastic bags during spraying to prevent this. Where bananas are grown on steep hillsides, it may be necessary for farmers to spray the trees by hand.
  
  

Freckle

• Freckle, Phyllostictina musarum, is a disease that blemishes fruit. It can also develop into a rotting disease; according to the University of Hawaii, the Brazilian cultivar is worst-affected. Fungicides to control freckle are available; the same issues with hilly plantations apply as with black leaf streak. In this case, however, it may just be easier to cover fruit with a plastic bag to prevent infection.