Yield loss caused by Zucchini lethal chlorosis virus (ZLCV) on zucchini squash 'Caserta'

Abstract

O ZLCV é um tospovírus encontrado com freqüência causando severos danos em cucurbitáceas. Nesse trabalho avaliaram-se os danos causados pelo ZLCV em abobrinha de moita 'Caserta', em campo na ESALQ/USP, Piracicaba-SP, onde esse vírus é freqüente. Plantas obtidas pela semeadura direta foram monitoradas periodicamente quanto à infecção pelo ZLCV por meio dos sintomas e por PTA-ELISA. Monitorou-se ainda a contaminação com Papaya ringspot virus - type W e Zucchini yellow mosaic virus, desconsiderando a produção dessas plantas. As plantas foram agrupadas em função da época de aparecimento dos sintomas do ZLCV, avaliando a produção de frutos comerciais (FC) e não comerciais (FNC) de cada grupo e comparando com a de plantas que permaneceram sem sintomas até o final do experimento. As plantas que apresentaram sintomas até os 23 dias após a emergência (DAE) não produziram qualquer tipo de frutos. FC foram colhidos de plantas que apresentaram sintomas a partir dos 42 DAE. Mesmo assim, houve redução de 78,5 % na produção de FC. Plantas que mostraram sintomas por ocasião da última colheita (55 DAE) apresentaram redução na produção de FC de 9,6 %. A infecção com o ZLCV até o início da frutificação inviabiliza a produção de FC de abobrinha de moita 'Caserta'.Zucchini lethal chlorosis virus (ZLCV) is a tospovirus frequently associated with severe yield loss on cucurbit crops. The purpose of this work was to evaluate the damage caused by this virus on zucchini squash (Cucurbita pepo cv. Caserta) under field condition. The experiment was carried out at the Campus of the College of Agriculture, University of São Paulo, Piracicaba, SP, Brazil, were ZLCV is prevalent. After germination, zucchini squash plants were periodically monitored for the presence of characteristic symptoms induced by ZLCV and PTA-ELISA for virus indexing. Infection by Papaya ringspot virus - type W and Zucchini yellow mosaic virus were also monitored by PTA-ELISA, and plants infected by these viruses were disregarded for yield evaluation. Plants were grouped based on the time the symptoms were first seen. Fruits harvested from each plant within each group were classified as marketable (M) and non-marketable (NM) based on the phenotype. Plants that did not show symptoms by the end of the crop were considered healthy and their yield was used as control. Zucchini squash plants that showed symptoms of ZLCV infection up to 23 after emergency did not yield any fruit. Marketable fruits were first harvested only from plants that showed symptoms 42 days after emergency. However, the yield of marketable fruits was reduced by 78.5 %, as compared to that from asymptomatic plants. Plants that showed symptoms 55 days after emergency showed a reduction on the yield of marketable fruit of 9.6%