Murcia-based Lemon and Grapefruit Interprofessional Association (Ailimpo) has raised concerns about a new disease that has appeared in the nearby Valencian Community. 

Photo: Plant Health Service, Valencia Government

In a release, Ailimpo drew attention to detections of Amycosphaerella Africana - which causes greasy spot in citrus and leaf spot in persimmons - in Valencia, and made a call for monitoring in Murcia.

"Especially important is vigilance and the early detection in lemon groves," the group said.

In an alert, Murcia's Council for Water, Agriculture and the Environment said the first signs of the disease included low levels chlorosis on foliar limbs which then develop necrotic pustules on the underside of the leaves.

Afterwards, the chlorosis becomes more generalized and leaves start to fall, leading to high instances of defoliation on trees.

The Council however warned these symptoms could also be similar to those produced by some phytosanitary treatments, as well as weather-related damages like sunburn or low temperatures. Therefore it is pertinent that laboratory analysis takes place to ensure the correct diagnosis has been made.

The fungus is carried through the air and reproduces through spores that form in leaf litter in the soil after a long incubation period. Infections are more likely when conditions of rain or moisture and temperature are adequate, generally during the months of spring and fall.

After the initial infection, it takes a few months before trees start developing symptoms, and in general the leaf lesions start to appear in the following year.

If a positive detection is made, the Council recommends one or two copper-based foliar treatments during spring and fall, combined with pruning beforehand in order to eliminate some of the contaminated leaves. 

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