Insect Pests:
Aphids, cyclamen mites and thrips are the most common pests of Hiemalis Begonias. Aphids can be controlled with Orthene® on a see-and-treat basis. Cyclamen mites damage foliage and growing tips, causing distortion and curling, and can be controlled with Thiodan®. If thrips become a problem they can be controlled with Talstar®, Avid®, Mavrik®, Duraguard®, or Margosan-O®. However, sprays must be applied every four to five days for at least two weeks to control a thrips population. Yellow sticky traps are recommended for detecting low populations of thrips.
Diseases:
Powdery Mildew: Powdery Mildew is the most frequent disease problem. It appears as a fine, gray to white fungus growth on foliage. Bayleton® 25WP is effective as a preventative spray, but also has a growth regulator effect. Apply only as a fine mist at the rate of 2-4 oz in 100 gallons of water (0.8 grams in 4 liters of water) after flower initiation. Karathane®, Systhane®, Rubigan®, and Strike® are effective as eradicant (curative) sprays. Karathane® may cause burn if sprayed on open flowers.
Bacterial Blight (Xanthomonas Begoniae): Small water-soaked spots appear, usually at the leaf margin, and eventually become surrounded by yellow or tan discoloration, depending on foliage color. Old lesions turn dry and small dark spots are evident within the dried tissue. Bacterial blight cannot be cured, only controlled by following strict sanitation procedures.
Gray Mold or Botrytis Blight: Fungicides such as Chipco® 26091, Daconil®, Domain®, Termil®, Decree®, and Compass® can help prevent Botrytis. Proper venting, heating and spacing limit conditions favorable for Botrytis development.
Foliar Nematodes: The use of Vydate® in conjunction with good sanitary practices help control nematode introduction and spread.
Root Rot: Pythium is the most common of several fungi that cause root rot of Hiemalis Begonias. A Subdue®/Chipco 26019® drench will help alleviate root rot.