Hariyali and nutgrass are the common weeds in pineapple plantations. Weeding is important from the economic point of view. Hand weeding especially in closely spaced crop is cumbersome and uneconomic. Therefore chemical control of weed is advisable. Application of Diuron at 3 kg/ha or combination of Diuron (1.5 kg/ha) + Bromacil (2.0 kg /ha) as pre-emergence spray is recommended. It should be repeated with half of the dose, 5 months after the first application. Irrigation followed by the herbicide spray helps in carrying herbicides to the root zone of the weeds.
Pre-emergence (within a few weeks after planting) spray of diuron @ 1-1.5 kg/ha in 600 litres of water can also keep the field free of most weeds for about four months. For subsequent weed control, herbicide application is repeated. For controlling Mikania micrantha (vayara valli or American valli), spot-application of diuron can be adopted. Spraying should be done in moist soil, but avoiding rainy periods. Weeds in interspaces can be controlled by spraying glyphosate 0.8 kg/ha or a mixture of 2,4-D 0.8 kg/ha. While spraying in interspaces, care should be taken that the herbicide shall not fall on pineapple plant.