At some stage a grower will see thin spindly pale plants growing somewhere in the greenhouse. Although not a physiological disorder of fruit, it is a disorder of the plant as a whole. Quite often plants grow to become long and stretched out. The leaves may even be smaller than usual and the colour of the leaves are slightly lighter than normal. If these symptoms are spotted all alarms must go of. I might be a simple problem or a complex mixture of factors affecting the plant, but the sooner it is solved, the quicker the plants can revive. I must be noted that when these symptoms are noted, there will be a reduction in yields which cannot be regained.
These spindly plants are caused by a number of conditions:
- The plants are not receiving enough sunlight which can be caused by old plastic and needs to be replaced. To high shade cloth percentage used or there was a long overcast period. There might be a tree close to one of the greenhouses that cast a shade during the day that can influence plant growth.
- The environment is to hot for the plant. Adjust the ventilation inside the greenhouse or if it is grown under shade cloth, replace with a higher density.
- If the plants are grown in a greenhouse, consider installing evaporative cooling pads (also known as wet walls) or a fogging system, or installing additional thin white cloth in the inside of the tunnel to reduce radiation which heats the plants.
- The variety used might not be adapted to the climate of the area.
- Check the nutrient solution. Quite often there is a mis-calculation of the nutrient solution such as Nitrogen. The effect can be seen within a couple of days especially if inert growth media is used.
It is important to consider the help of an expert (advisor or consultant) since the problem can be complex.