Hektar

WHITE SPOT OF TOMATO LEAVES – Septoria lycopersici

Symptoms of the disease (characteristics for the diagnosis of the disease)

• the disease manifests itself on the leaves by the appearance of circular spots with a diameter of 0.5-1 mm, which in favorable conditions can reach 3-4 mm, the tissue near the spots are brown at first, then gray-whitish with their edge bordered by a dark brown ring;
• similar spots can be observed on the petiole of the leaves, on the stems and sometimes on the fruits
• with early attack, they can be partially or totally destroyed on seedlings.

Factors favoring the occurrence and evolution of the disease, its transmission and spread

• the disease is found in tomato crops in the field in years with abundant precipitation, the average temperature of 22-26ºC;
• the attack always starts on the leaves at the base;
• the fungus can overwinter on tomato leaves and sick plant stems in the soil or on the soil surface; apart from tomatoes, the pathogen can also overwinter on Datura stramonium, Solanum nigrum, Solanum tuberosum, Solanum melongena, etc.

Prevention and control measures

• Agrophytotechnical Measures: Implementing effective agrophytotechnical strategies is crucial for managing plant disease attacks and their progression. Key practices include collecting and disposing of plant residues, conducting deep plowing, rotating crops, eliminating weeds that serve as hosts for pathogens, and ensuring proper ventilation in propagation greenhouses. These measures contribute to producing robust and healthy seedlings for field planting.
• Foliar Treatments: During the growing season, foliar treatments will be applied using products such as: Chlorothalonil (Bravo at 0.4%); Metiram (Polyram DF at 0.2%); Mancozeb (Dithane M45 at 0.2%, Dithane 75 WG Neotec at 0.2%, and Manzate at 0.2%); and a combination of Pyraclostrobin and Metiram (Cabrio Top at 0.15-0.2%).
• Ecological Alternatives: Ecological products serve as an alternative to conventional chemical controls. For instance, Copfort acts as a fortifier and defense inducer when applied foliarly at a concentration of 0.15-0.30%. It penetrates the cuticle effectively, prompting the plant to synthesize phytoalexins that inhibit the growth of Septoria spp. fungal hyphae.
• Biostimulants: Additionally, foliar biostimulants can help prevent factors that encourage disease emergence. Notable examples include AXEKELP PLUS and AXEMIN PW40, both applied at a concentration of 0.3%.