Begonias make excellent and rewarding house plants.They need warm, humid and well-lit conditions but not direct sunlight.Generally,Begonias grown indoors will require some shading during summer.In winter a minimum night temperature of 12deg c(54 deg f)will suit many species, but avoid placing plants near central heating.An open,humus-rich compost is suitable for most Begonias.Feeding should be undertaken regularly during the growing season.
Overwatering can be a common source of problems with Begonias,especially in winter and can cause rotting.To avoid getting the foliage wet,it is best to water from below.Keep plants clean and healthy by regularly removing old blossoms and damaged leaves.
Pests and diseases.
The most serious disease to affect Begonias is Powdery Mildew caused by Microsphaera Begoniae.White,powdery patches appear on the stems and leaves, especially under humid conditions.The best control is to ensure even watering,preferably from below,and adequate ventilation.It may be necessary to spray with carbendazim(such as Bio Supercarb,Doff Plant Disease Control or AgrEvo Garden Fungicide),bupirimate plus triforine (Nimrod-T), penconazole(Murphy Tumbleblite 2)or myclobutanil (Bio Systhane).
A bacterial leaf spot and blight can be very destructive. Caused by Xanthomonas Campestris Pathovar Begonia,it is important to avoid importing the disease on infected plants.Infected tissues should be cut out and the humidity reduced to lessen the risk of reinfecting cut surfaces.There is no labelled chemical cure,but copper fungicides are effective against some other bacterial diseases,and dusting tubers with sulphur (Vitax) may be helpful.Some Begonia rex cultivars are relatively resistant,but it is necessary to destroy affected susceptible plants.Some viruses are damaging, especially Tomato Spotted Wilt Virus spread by thrips.Affected plants should be destroyed.Begonias are prone to Oedema,induced by irregular watering, causing blisters then corky patches on leaves and stems.
Leaf and bud eelworm and tarsonemid mites are two pests for which amateur growers have no controls apart from disposing of affected plants.Yellowish-brown wedges,bounded by the larger leaf veins, are an indication of eelworm attack on the foliage.Tarsonemid mites feed by sucking sap in the shoot tips, causing stunted and distorted foliage and flowers.Vine weevil grubs feed on the roots and corms.
Protect plants by growing them in Levington Plant Protection Compost or use a nematode treatment(such as Defenders Grubsure™)in late summer. Aphids are an occasional problem that can be controlled by spraying with Miracle Rapid.Tortrix moth caterpillars bind leaves together with silk and are best dealt with by squashing these leaves between finger and thumb.
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