Remember, it is far easier to avoid getting a problem than it is to get rid of it. The pest avoidance practices described above eliminate most problems with soil borne diseases. The most common leaf disease problem in the greenhouse is powdery mildew. Many of the cucurbits grown in our greenhouses are used for research projects involving an evaluation of disease symptoms on leaves. Scouting for diseases can be very helpful in keeping this disease controlled.
Weeds Soil steaming eliminates the requirement for most weed control practices in the greenhouse.
An exception to this is the pesky weed Oxalis . The seeds of Oxalis and clover are resistant to steaming. The seed capsules also shoot the seeds out when touched and the seeds stick to stems, pots, people and walls. The seeds may later be washed down into the soil to continue the pest problem. It is important to pick the Oxalis out of pots before seed pods develop.