Data on the viral load distribution by different leaves parts (upper, middle, lower leaves) in cucumber plants grown in protected ground are presented. Studies were conducted at the time of the visible infection manifestation. It was revealed that accumulation of virions of the cucumber green mottle mosaic virus (CGMMV), with the onset of manifestation, prevailed in the middle and lower leaves, which is probably due to the "slow" redistribution of the virus along the external phloem. This pattern is confirmed by a high correlation coefficient (r = 0,99). It was also found that the viral load indicator has high variability (C v = 63,77%). A similar coefficient of variation may indicate the fact that under constant environmental and nutritional conditions, which are provided under the conditions of protected ground, the individual susceptibility of cucumber plants to the phytopathogen affects the number of viral particles in the plant.

The article presents data from laboratory experiment on the artificial infection of cucumber plants with the green mottle mosaic virus in different concentrations. The dynamics of virus accumulation in each of the experimental groups is described. There is an association for which stage of viral load that correlates with the onset of visible signs of infection and a further increase of the disease symptoms. The obtained data showed that the virus accumulation in the plant obeys the exponential equation. When constructing a graph of the accumulation of viral load, it was noted that the onset of visible manifestations of the disease falls on the linear segment of the curve, and the mosaic manifestation on the exponential segment. The dependence of daily average growth on the virus concentration has not been established. Based on the results of the experiment, we can give reasonable recommendations on the use of quantitative PCR analysis in predicting outbreaks of viral infections in greenhouse complexes based on the viral load in the plant during disease symptoms absence.