Abstract

An inquiry and a field study was made among protected cultivation growers to chart how rehabilitation in greenhouses is carried out in protected cultivation in Sweden today. The inquiry was replied by 108 growers of which 31 was vegetable growers, 68 ornamental plant growers and 10 growers of both vegetables and ornamentals. Plant deliveries to the cultivations were found to have a major responsibility for the spread of plant diseases and insects to the greenhouse cultivations, especially for ornamental growers. Ornamental growers had larger problems with insects than vegetable growers (82% and 61% respectively) in the inquiry. As regards fungi, the situation was the opposite. More vegetable growers (84%) had fungi problems compared with those who grew ornamentals (47%). Both the inquiry and the field study showed that an accurate rehabilitation, with emptying of the house of all plants and materials (so called total rehabilitation), gives a good result in lowering the pressure of pathogens which helps the new plants to get a good start. In total rehabilitation it is important to clean the house carefully to remove organic matter. The reason for this is that the organic matter is a good growing media for all kind of damaging insects and fungi, bacteria and virus diseases. All surfaces should be cleaned carefully with water, either with a high pressure sprayer or with a brush or a sponge, preferably with some washing agent in it. Even the outside shell of the house should be washed with water under high pressure. After the washing, the house could be treated with some kind of chemical. The most effective chemical today for combating fungi in the greenhouse is formaldehyde. Formaldehyde is unhealthy and unpleasant to work with and it is a good idea to let a contractor perform the chemical treatment. Other aldehyde preparations, like Korsolin, Glucid or Lysovet-PA, could also be used. Quaternary ammonium compounds like Menno-ter-forte or Groen-ex can be used, but are less effective. The advantage of the latter compounds is that they are less unhealthy and unpleasant to work with. Before with chemical treatment the temperature and the relative humidity must be kept high and the house must be sufficiently air-tight to permit an even spray distribution. When performing the treatment the weather should be calm, that is especially important if the treatment is performed with small particles / droplets as when fogging or using aerosol. In windy weather, the spraying distribution will be uneven and some of the liquid will be lost out of the greenhouse. If the treatment is done under "bad" conditions, for example low temperature, chemicals may remain in the house afterwards and have negative effects on plants and biological control. When used under adequate conditions fogging is suitable for chemical application in the empty greenhouse thanks to the droplets that cover all surfaces. The investigations made in this study do not prove that chemical treatment garantees a good rehabilitation result, but it indicates that a careful washing is the most important measure in rehabilitation. After the rehabilitation has been done, hygienic measures must be taken in all parts during the growing season to ensure a low pest and insect pressure. Otherwise the rehabilitation might just as well not have been made at all.

Keywords

sanering; odling under glas; odlingshygien; rengöring; kemisk bekämpning; ångning; dimning; sprutteknik; arbetsmetodik; metoder; saneringsstrategi; växtskydd; appliceringsteknik; växthusteknik

Published in

Rapport - Sveriges lantbruksuniversitet, Institutionen för lantbruksteknik
1990,
ISBN: 91-576-4147-1
Publisher: Institutionen för lantbruksteknik, Sveriges lantbruksuniversitet

Permanent link to this page (URI)

https://res.slu.se/id/publ/125626