Hello. The symptoms are specific to a phytopathogenic disease (possibly fungal, such as Septoria leaf spot, or bacterial), but only from the attached photos and at this stage of the disease it is difficult to identify exactly.
In this case, it is recommended to remove the affected leaves and make a first treatment with a fungicide such as , in a dose of 20g/10 L water, and 7 days after this, you can make a second treatment with the fungicide: , in a dose of 10 ml/10 L water, applied by spraying the leaves. It is recommended to carry out the treatments early in the morning, when temperatures are not very high. Subsequently, for disease and pest control, you can consider preventive treatments during the vegetative growth period, depending on the phenotype.
Also, in order to avoid nutrient deficiencies and to ensure healthy growth of tomatoes, it is important to fertilize the plants using specific fertilizers: , , or , applied according to the label recommendations.
In addition, for more information on the environmental and care conditions specific to this crop, please consult our articles: Tomatoes, information about crop management; Nectarine Care: Planting, Growing, and Harvesting Tips; Tomatoes, treatments against pests and diseases.