Salicylic acid
There are several host factors that affect disease development. For example, various signaling pathways in tomato plants affect their susceptibility to AAL. Salicylic acid promotes resistance to AAL and antagonizes the ethylene response. Ethylene controls the synthesis of jasmonic acid, which is a necessary pathway for susceptibility. Independently of each other, salicylic acid, ethylene, and jasmonic acid can influence the susceptibility of tomato to AAL. Diagnosis of AAL is often from observing signs and symptoms from this fungal pathogen. In addition, a tomato cultivar's resistance to a toxin produced by AAL also affect disease development. Please see the Pathogenesis section for more details on this process.