Good air circulation and plenty of ventilation are a must for a greenhouse grower. This type of mildew is usually present when the temperature is cool, and the humidity is high. Powdery mildew is a white, powdery substance on the topside of leaves, buds and stems. Traps and pellets will be more practical for a profuse infestation. They can be controlled by applying diatomaceous earth around the base of the plant in a 2” wide circle. A reliable method to stop the transfer of these pests is to sterilize the pots or application of a soil drench if they are in infected soil.Ī telltale sign of a slug or snail in your Begonia garden outdoors is the presence of mucus and round holes in the leaves. This often leaves the foliage void of substance, discolored, distorted, or wilting. Root nematodes are soil-borne and attack the begonia’s root system. Avoid overhead watering and wetting the leaves. Practice good plant care by removing dead and decaying leaves from plants as well as from growing racks and benches. Reddish-brown, dead areas on leaves and stunted growth are signs that this nematode may be present. This setting is prime for them to move from plant to plant. Leaf nematodes are a problem in terrariums or greenhouses due to their need for a moist, humid environment. Nematodes are parasitic, microscopic worms that come in two types: leaf and root. Predatory wasps may be beneficial in a greenhouse setting. Spray 6–10 days apart to kill the larvae that are constantly hatching. Yellow, sticky traps suspended near the plant will attract and catch them. They are found on the undersides of leaves and, if disturbed, will fly to other plants. White flies are very small, white insects that can fly. Treat infections at regular intervals, until scale is gone. The treatment of this insect is the same as mealy bugs. Hard scale has “armor” on its back and doesn’t produce any residue. Soft scale produces a honey-like residue. Two kinds of scale may be found on begonias: soft and hard. Scale are small, roundish insects with a hard shell on their outer surface.

Several treatments may be required to eradicate this critter. If the area is large, spraying or dipping in soapy water will be the method of control. A cotton swab saturated with rubbing alcohol usually controls a single site infestation. A “wooly” material is secreted around its egg masses. The body of a mealybug is soft, white, and wax-like.

Wax begonia soil