  Plant diseases are responsible for substantial and sometimes devastating
economic and societal costs and thus are a major limiting factor for stable and
sustainable agricultural production. Diseases of crops are particular crippling
in developing countries that are heavily dependent on agriculture for food
security and income. Various techniques have been developed to reduce the
negative impact of plant diseases and eliminate the associated parasites, but
the success of these approaches strongly depends on population awareness and
the degree of engagement with disease control and prevention programs. In this
paper we derive and analyse a mathematical model of mosaic disease of {\it
Jatropha curcas}, an important biofuel plant, with particular emphasis on the
effects of interventions in the form of nutrients and insecticides, whose use
depends on the level of population awareness. Two contributions to disease
awareness are considered in the model: global awareness campaigns, and
awareness from observing infected plants. All steady states of the model are
found, and their stability is analysed in terms of system parameters. We
identify parameter regions associated with eradication of disease, stable
endemic infection, and periodic oscillations in the level of infection.
Analytical results are supported by numerical simulations that illustrate the
behaviour of the model in different dynamical regimes. Implications of
theoretical results for practical implementation of disease control are
discussed.
