A virulent pest which has been attacking many species of plants particularly in the Western Province is causing harm and damage at levels never seen before. Milky sap plants such as temple tree (Frangipani), jackfruit, breadfruit, papaya, rambuttan, croton and other foliage plants, as well as citrus in home gardens and households have been severely affected and at a loss as to how to control this outbreak. Common symptoms caused by this species include a white powdery substance mainly on the underside of leaves.
Mealy Bug infected Fruits, Foliage and Ornamental Plants
Hayleys Agro Products Limited has mobilized its team of extension staff and is conducting educational campaigns through its mobile units as well as arranging control measures such as spraying programmes. Households in Colombo and suburbs have made use of the advisory services available within Hayleys Agro. In conjunction with the Department of Agriculture, Hayleys Agro recommends the following course of action:
Identification of Pest and Symptoms
- Identify mealy bugs by looking on the undersides of leaves, along leaf veins, on growing tips and around leaf joints. These insects look like small (1/10 to 1/8 of an inch) balls of cotton / white powdery residues are found on the infected plants
- Mealy bug-damaged plants look withered and sickly and may have sticky sap on the leaves and stems.
- Mealy bugs damage plants by removing plant juices and by spreading diseases. They feed on all parts of a plant, particularly new growth. Yellowing of leaves or leaf drop may be a symptom of an infestation.
- Mealy bugs excrete a honeydew substance over plant surfaces. This causes a secondary fungus called sooty mould (black colour) to grow on the mealy bug excreted substance causing the plant foliage to look like it is covered with chimney soot.
Mode of Disease Transfer
- Mealy bug is transferred mainly through ants
- Cocoons are also transferred through wind
- Can be transferred through birds
- It can also be transferred through infected plants, equipment and humans
Treatment Measures
The following controls may result in reducing an infestation. Eradication of mealy bugs will only happen by persistent application of controls.
- Cut and destroy by burning or disposing off highly infected plants/ infected plant parts (including the leaves that have fallen on the ground)
- Spray a strong jet of water directly on to the affected area of the plant. The stream washes the insects off. This is the easiest way to control mealy bugs.
- Spray with a soap water solution (2 tsp washing power, 1 tsp kerosene mixture in 1 litre of water for non-edible plants).
- Spray shampoo mix every once in 2 days for edible plants
- Apply grease on the bark to avoid re-infestation. (2” – 4” wide belt)
- Spray infected plants with 1 -2 ml of Admire SL 200 in 1 litre of water (chemical control)
About Mealy bug
Mealybugs are part of the insect families collectively known as scale insects. Mealybugs are in the Family Pseudococcidae, and are the least scale-like of the group, mainly because they are soft-bodied, without the outer shell associated with insects in the other scale insect families (Diaspididae, the armored scales, and Coccidae, the soft scales). Instead, mealybugs are usually covered with a white waxy powder, and have filamentous projections around the perimeter. Some of these projections can be quite long. At present, the mealy bug reported in Sri Lanka is the papaya mealy bug known as Paracoccus marginatus. Other mealy bug pest species include the citrus mealy bug, Planococcus citri, and the long tailed mealy bug, Pseudococcus longispinus. Recently, another mealy bug species, the hibiscus mealybug (Maconellicoccus hirsutus) has the potential to become a problem on numerous ornamental crops. Mealybug pests have in common the ability to feed on a very wide range of host plants.
The life cycle length ranges from about 30 days, but due to high temperature the life cycle have been shortened to 7 – 15 days
Life Cycle and Habits:
Mealy bugs can reproduce by laying eggs or by bearing live young. Eggs hatch in ten days. The nymphs, which are pale yellow, begin feeding immediately. The young nymphs remain in a "crawler" stage for a short time. Gradually a white fluffy, waxy coating begins to form over their bodies. As the coating gets thicker, the nymphs' movements become sluggish.
Females molt twice before becoming adults. Males have an additional pupal stage spent in a thin cocoon. During this period they develop wings. The males have no mouthparts. Their only purpose in life is to grow wings to fly, find a female (who is wingless) and mate with her. There may be several generations of mealy bugs per year.
Hot, dry weather offers favorable growing conditions for mealy bugs.
For further information please contact:
General Line: 2688960 - 3
Mr. K. A. K. Boralessa: 077 2942736
Mr. S. M. Gamage: 077 2885079 |
