One of the main leaf diseases of tomato is the early blight, caused by the fungus Alternaria solani. The use of essential oils could be an alternative for controlling by acting plant defense against phytopathogens. The objective was to evaluate the antifungal, the early blight control, and the activity of defense enzymes in tomato treated with tea tree (Melaleuca alternifolia) essential oil. Aiming to evaluate the mycelial growth and sporulation of the pathogen, mycelial discs were placed in Petri dishes with 0, 500, 1000, 1500, 2000, and 2500 μL L⁻¹ of essential oil, and an additional treatment with fungicide (azoxystrobin + diphenoconazole). The treatments were applied onto the second pair of leaves of tomato plants grown in a greenhouse, and after three days the pathogen was inoculated in the second and third pairs of leaves. Severity was expressed through the area under the disease progress curve (AUDPC). The peroxidase, polyphenoloxidase and phenylalanine ammonia-lyase activities were evaluated with the concentration of 1500 μL L⁻¹. Mycelial growth showed a linear decrease as concentrations increased. In the treated leaves, the 1500 μL L⁻¹ concentration showed the most reduction in AUDPC, corresponding to 53%, whereas in the untreated leaves, the most effective concentration was 2000 μL L⁻¹ with 42% inhibition. An increase in peroxidase and phenylalanine ammonia-lyase activities were observed in the tomato leaves. Tea tree essential oil can be an alternative for the control of early blight in tomato.

番茄的主要叶病之一是早疫病，由真菌链格孢菌引起。精油的使用可能是通过对植物病原体进行植物防御来进行控制的替代方法。目的是评估用茶树（互叶白千层）精油处理的番茄的抗真菌、早疫病控制和防御酶的活性。为了评估病原体的菌丝生长和孢子形成，将菌丝盘放置在具有 0、500、1000、1500、2000 和 2500 μL ^{-1 的}培养皿中精油，并使用杀菌剂（嘧菌酯 + 苯菌灵）进行额外处理。将这些处理物施用于温室中生长的番茄植株的第二对叶子，三天后将病原体接种在第二对和第三对叶子中。严重性通过疾病进展曲线下的面积 (AUDPC) 表示。过氧化物酶、多酚氧化酶和苯丙氨酸解氨酶活性在1500 μL L ^-1的浓度下进行评估。随着浓度的增加，菌丝体生长呈线性下降。在处理过的叶子中，1500 μL ^-1浓度显示出 AUDPC 的最大降低，相当于 53%，而在未处理的叶子中，最有效的浓度为 2000 μL L ^-1抑制率为 42%。在番茄叶片中观察到过氧化物酶和苯丙氨酸解氨酶活性增加。茶树精油可以作为控制番茄早疫病的替代品。