Articles
IMPLICATIONS OF THE USE OF EXCESS COIR DUST MULCH IN PINEAPPLE CULTIVATION ON THE MEALYBUG WILT DISEASE OF PINEAPPLE
The pink pineapple mealybug, Dysmicoccus brevipes Cockerell, causes the wilt disease.
Ants attending on the mealybug colonies (tending ants) play a major role in the build-up of the mealybug colony and thereby the disease.
Pineapple is planted in rows, leaving 1.5 to 2 m avenues between rows.
The weeds in these avenues are managed in several ways.
In this experiment, pineapple was planted in three blocks, 15 to 22 m apart from each other and the impact of three common weed management practices: 1. Clean weeding 2. Slash weeding and 3. Mulching with excess coir dust, on the ant/mealybug/spider population and fruit yield was studied in these 3 blocks.
Each block was planted with 966 plants in an area of 694 m2.
Pitfall traps (12/block) were used to monitor the ant/spider numbers per week.
Mealybugs when incident on the crop, were counted weekly in each plot.
Ant species were identified and counted weekly.
The experiment was carried out for a period of 2.8 years.
The results showed that mean number of tending ants was higher in the (T3) coir dust mulched plot (48/plot/week) than in the (T1) clean weeded (26/plot/week) or (T2) slash weeded (39/plot/week) plot.
Consequently mean numbers of mealybugs were also higher in the (T3) coir dust mulch treatment (480/plot/week) than in the (T1) clean weeded (264/plot/week) or (T2) slash weeded (416/plot/week) treatment.
Mean numbers of the ant Paratrechina longicornis (Latereille) was higher in T3 (21/plot/week) than in T1 (9/plot/week) or T2 (8/trap/week) plot, while mean numbers of Camponotus spp. were higher in T2 (13/plot/week) than in T1 (7/plot/week) or T3 (7/plot/week).
Fruit yield during the first fourteen months was higher in T1 (2053 kg/plot) than in T2 (1103 kg/plot) or T3 (1970 kg/plot) plot.
As a first step towards the management of the wilt disease, it is important to minimise ant numbers and remove weeds between rows and limit use of coir dust mulch to base of plants along rows.