6% of. the sunlight which reaches the earth is ultraviolet light. This light has great importance and effect on crops. UV light helps plants to grow, affects color improvement on vegetables and flowers. UV light, is also important for plant diseases and insect behaviours. Most of the insects need UV light too see the plants.

Lack of UV light confuses the insects. Insects suck on the plants to get the juice and they prefer especially the young leafs of vegetables and flowers.

If the entrance of UV light inside the greenhouse is blocked by additives in the greenhouse film, the activities of white flies and several other insects becomes impossible. Because the UV light is not present in the greenhouse these areas become dark and insects leave the greenhouse. Since the upper region of the greenhouse is much darker the insects and flies cannot reach these upper regions where the young leafs of the plants are existing. The leafs in lower parts are old and rough so they are not suitable for these insects. Since these insects cannot live in the greenhouse they cannot infect the plants with the viruses and diseases they carry, or it can only happen at a minimum. The additives which are present in the greenhouse film is proven to protect to a great extent the Upper Yellow Leaf Mosaic Virus, which is carried by the white flies and seen mostly in tomatoes. Besides they are useful in controlling the fungus disease seen in plants and flowers.

Another use of these additives in flower greenhousing is to prevent the black spots on the red roses, which are decreasing the value of the roses.

But as we mentioned in the beginning, plants also need UV light to grow so it is not desired to block these lights completely. For example, some white roses need UV light to reach the right color shade. In such cases the usage of additives should be minimum or none at all. The additives are selected carefully not to block all of the UV light. The aim is to keep the transparency of the greenhouse film. The effect of such additives do not continue forever, the effective time 24 months for now.