Plants can be induced to develop enhanced resistance to pathogen infection by treatment with a variety of abiotic and biotic inducers. Biotic inducers include infection by necrotizing pathogens and plant-growth-promoting rhizobacteria, and treatment with nonpathogens or cell wall fragments. Abiotic inducers include chemicals which act at various points in the signaling pathways involved in disease resistance, as well as water stress, heat shock, and pH stress. Resistance induced by these agents (resistance elicitors) is broad spectrum and long lasting, but rarely provides complete control of infection, with many resistance elicitors providing between 20 and 85% disease control. There also are many reports of resistance elicitors providing no significant disease control. In the field, expression of induced resistance is likely to be influenced by the environment, genotype, and crop nutrition. Unfortunately, little information is available on the influence of these factors on expression of induced resistance. In order to maximize the efficacy of resistance elicitors, a greater understanding of these interactions is required. It also will be important to determine how induced resistance can best fit into disease control strategies because they are not, and should not be, deployed simply as "safe fungicides". This, in turn, will require information on the interaction of resistance elicitors with crop management practices such as appropriate-dose fungicide use.

This paper summarizes an extensive investigation of the thermodynamic interactions that govern phase behavior in blends of polyolefins and examines their relationship to pure component PVT properties. Interaction strengths, obtained by small-angle neutron scattering (SANS) measurements, were classified as regular or irregular according to their consistency with a solubility parameter formalism. Characteristic pressure P* and temperature T* were obtained from PVT data on the pure components with various liquid-state models. For the regular blends, a close correspondence was found between the SANS-based and PVT-based solubility parameter assignments, the latter being closely related to P*, as expected. The pattern of deviations for the irregular blends, positive in some and negative in others, effectively ruled out equation-of-state contributions as a general explanation. However, the results suggest that mismatches in both P* and T* play some role, and we offer some tentative attempts at generalization.

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