STABILITY ANALYSIS OF DYNAMICAL MODEL INTERACTIONS TEA PLANTS, PESTS, AND DISEASES WITH FUNGICIDES AND INSECTICIDES CONTROLS

Tea plants are one of the exports commodities in Indonesia. In their development, plantation ecosystem is heavily influenced by several factors, both internal and external factors. field applied mathematics, mathematical modelling can be used to analyze development tea plant growth interactions each other ecosystem. The model this research combining three main models, there logistic model, epidemiological predator prey adding fungicide insecticide controls. Furthermore, local global stability analysis carried out optimal control problem solved Pontryagin maximum principle. results obtained five equilibrium points. Local was using Routh Hurwitz criteria which showed fifth point locally asymptotically stable. basic reproduction number 0.99. Because 16R0<1" style="width: 28pt; height: 11pt;">, it concluded that no spread disease after a period 5 years. provided reduce pest attacks. After being given control, population infected decreased 93.21%, Empoasca pests 99.47%, leaf roller caterpillars 99.31% compared not control.