Preliminary Study on the Control of Cucumber Green Mottle Mosaic Virus in Commercial Greenhouses Using Agricultural Disinfectants and Resistant Cucumber Varieties

Cucumber green mottle mosaic virus (CGMMV) is a re-emerging threat to greenhouse cucumber and other Cucurbitaceae crop production worldwide. This seed-borne virus can easily spread from a contaminated seeds to seedlings and to adjacent plants through mechanical contact of the foliage of diseased and healthy plants causing extensive yield losses. Additionally, infection may not be limited to the current crop but may also affect subsequent crops due to the long-term persistence of the virus on contaminated crop residues, greenhouse hard surfaces and soil or soil-less greenhouse substrates. In the present work, three greenhouse experiments were conducted to develop an integrated pest management strategy towards controlling CGMMV in commercial cucumber greenhouses, by implementing an effective sanitization program and using resistant and grafted cucumber varieties. Results of sanitization highlighted that pressure washing and cleansing with an alkaline foam cleanser eliminated CGMMV on some of the most heavily infested areas. However, three successive applications of cleanser and disinfectants were essential to completely eliminate CGMMV on porous and uneven surfaces, such as cement alleyway, tray gutters and floor mats. The screening of 15 cucumber varieties revealed that one Mini ('Khassib') and three Long English ('Sepire', 'Bomber' and 'LC13900 ') had reduced or delayed CGMMV infection spread in the greenhouse but were intermediate in yield. The most resistant Mini variety was 'Katrina'. This variety showed low CGMMV infection level and high fruit yield. The varieties 'Jawell', 'RZ 22-551 ', 'Sunniwell', 'Bonbon' and 'Dee Lite' were the most tolerant to CGMMV. They showed a high CGMMV infection level without compromising yield. These results proved the need for new productive cucumber varieties with CGMMV resistance. Grafting experiments showed a yield increase only in the case of grafted 'Picowell' over 'Bonbon' but no CGMMV resistance, which is a much more desirable result of grafting experiments in order to have economic potential. In all, the current study revealed unique methods of CGMMV management in commercial greenhouses that are recommended to growers for reducing crop losses and improving economic returns.