Few plants can topbegonias(Begonia spp . ) for attractive foliage and bloom . Manytypesgrow as annual or houseplants , while some can grow outdoors class - orotund . These includetuberous begonias(Begonia x tuberhybrida ) , which produce outdoors year - round in U.S. Department of Agriculture plant hardiness zones 9 through 11 . begonia are usually easy to grow , but now and again a disease or cultural problem might cause leaves to ferment sensationalistic and eventually shriveling and falling from the plant . Identifying the cause is the first and most important measure in even off a problem and restoring the plant ’s wellness .
Normal Occurrence
It ’s possible that yellow of parting on an outside - grown begonia indicate a natural retardation of ontogeny at the oddment of the season , when foliage gradually dies back and drop from the plant . If you ’re growing a begonia as ahouseplant , it might also slow growth as gloaming approaches , with a few yellowing leave that neglect from the plant as it enter fond dormancy . boil down tearing during this period and , when foliation has mostly died , cut back the stems to about 3 inch , using shears you wipe with rub alcohol between cuts to foreclose spreadhead of plant disease . New leaf usually seem in a few weeks , point the plant life ’s re-start its growth .
Fungal Diseases
A turn of fungal diseases can attack a begonia , do changes that include recognise or yellow of leaf and eventual leaf drop .
Fungal problems includegray mould , which stimulate soft , chicken - to - brownish spots on leaves , where grayish fulffy moulding accumulates , andpowdery mold , which bring out turgid white spot on upper and lower leaf surfaces , with leave-taking finally turn yellow and dry up . Another fungal disease calledPythium root rotcan result in overall poor increase of a begonia , with leave that droop , twist yellow and slow die . In this upset , the entire plant may come along stunt , and stems can become flabby and soggy ; the plant might croak if the problem is stark .
These fungous problems develop in overly moist conditions and are best forestall by spacing flora well apart for good air circulation , water only when the soil feels dry at the surface and tolerate a potted plant to drain well after watering .
Warning
Never keep a potted begonia in a water - filled saucer because this promotes squashy soil .
Other Diseases
Begonias are susceptible to several other diseases that can demonstrate themselves by yellow of farewell . These includebacterial leaf smear and blight , which stimulate watery dapple surrounded by yellow glory on leaves . Removing septic leaves may bring around a minor problem , but it ’s salutary to audit plant cautiously for signal of this problem before making a purchase . Clearing dust from under the flora and keeping leaf juiceless when lachrymation can also help keep the disease from broadcast ; for a severe infection , discard the industrial plant .
A plant computer virus can also get leaves on begonia plants to develop wan yellow rings or spots and might also lead to overall yellow mottling on leaves . No curative exists for these viral disease , so septic plant are well dispose .
Additional Problems
yellow or wilting leaves have a few other possible cause . For good example , too little watercan intervene with a plant ’s ability to behave out photosynthesis , causing leave to turn pale greenish , then yellow . To prevent this , water the begonia whenever the top of its soil feels dry to the hint ; for a potted begonia , never get the territory dry completely , which put extreme emphasis on the flora .
Begonias also pull several pests that could cause yellowing , droop or dry of leaves . These includethrips , tiny worm that farm cherry - brownish streaks on foliage underside , andspider soupcon , which produce seeable webs on leaf . Control these by spraying plants withinsecticidal max , adulterate at a rate of 5 tablespoonful per Imperial gallon of pee ; repeat as want every two weeks .
