Monday, November 19, 2012

Diseases and Pests of Fruit

November 19, 2012
 A pest is any organism that negatively directly or indirectly affects fruit quality either pre- or post-harvest. Pests that attack fruit crops include bacteria, mollicutes: (Bacteria without cell wall, phytoplasmas), fungi, insects, weeds, and nematodes.

Then we have bacterial diseases that can cause damage to fruit, leaves, and stems. They spread by tools, wind, rain, and labor. They can be control with genetic resistance, chemical sprays, which may not be very effective, and sanitation. 

Bacterial Diseases and the Fruits they affect:
  •  Fireblight – apples, pears
  •   Citrus canker, greening -oranges, grapefruit 
  •  Bacterial canker – peaches
  • Bacterial Leaf Spot
  •  Crown gall - apples, peaches, cherry, grapes

Fungal Diseases can affect leaves, fruit, stems, and roots. They spread by soil and aerial means (rain). They can be control with genetic resistance, fungicides, and biological ways (natural).
Important Fungal Diseases and the Fruits they affect:
  •  Black sigatoka – banana 
  •  Fusarium, many crops – bananas
  • Brown rot – peaches, citrus
  • Black rot/ripe rot (postharvest) – grapes
  • Scab – apple, citrus, peach
  • Powdery mildew (dry environment) – grapes, apples, chestnut, cherries
  • Wilt – grapes, blackberries, raspberries
  • Anthracnose – avocado, mango

Mollicutes are similar to bacteria, lack cell walls, and survive on inorganic sources. They have a life-like similar to bacteria, and decline symptoms similar to viruses.

Important Mollicute Diseases and the Fruits they affect:
  • Witches Broom – Limes
  •  Stubborn Disease (spiroplasma) – Oranges
  • Pear decline
  •  Lethal Yellows (phytoplasma) – Coconut
  •  Grapevine Yellows

Virus Diseases are the most severe of all diseases. They spread by budwood, budding, grafting, insects, mites, nematodes, and pollen. They can be control with genetic resistance and heat therapy.

Important Virus Diseases and the Fruits they affect:
  • Citrus Tristeza: (mites)
  •  Apple Mosaic – apples, peaches (pollen)
  •  Papaya ring spot spread (Aphid)
  • Tomato ring spot - apple, stone fruits (Nematode)

Other Common Pests of Fruit Crops
  •  Insects
  •  Mites
  •  Animals – deer, moles/voles
  •  Snails

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