Growing plant is ordinarily an enjoyable and rewarding hobby , but it can be quite discouraging when a tough , generally trouble - spare shrub such asan oleander(_Nerium oleander _ ) develop a trouble that interferes with its ontogenesis or flowering . An African native , oleander grows in U.S. Department of Agriculture plant hardiness zona 8 through 10 , covering itself in showy , coloured bloom in summer . If you ’re grow an oleander and it starts doing poorly , an important first step is to distinguish the cause of the problem , then take appropriate disciplinal measures to restore its health .
Warning
All portion of an oleander are highly poisonous , so it ’s not a good alternative for an domain frequented by baby or deary . contact lens with the industrial plant can also cause skin irritation , so wear boxing glove when working on the flora .
Bacterial Diseases
Bacterial Blight
Bacterial blight is get by a bacteria calledPseudomonas syringae . You might see bud or vernal bloom die back , along with dice - back of green , growing tips . Leaf veins might darken or even turn black , and dismal spots could seem on parting . Dark , soft spots calledcankerscan also appear on the plant ’s stalk . To work out this problem , use shrewd shear to crop off any subdivision with symptoms , cutting behind the pathological domain and into healthy Grant Wood . Do this during teetotal weather , when re - contagion is less potential . No in force controls exist for this disease , but if symptoms only appear on leaves and bud and affected role are removed , the plant should recover ; a severe job that include main stems might kill the shrub .
Tip
Always pass over pruning blade thoroughly with rub alcohol between each stinger to prevent spreading disease .
Oleander Leaf Scorch
Oleander leaf scorch is triggered by growth of a bacterium calledXylella fastidiosa ; this organism causes leave to become yellow and sag , with folio margins eventually turning Robert Brown . These leaves eventually die and the disease can spread from ramification to limb , especially during ardent weather condition . symptom resemble those of lack of water , but only feign some branches , helping distinguish it from problem arising during drought that affect the entire plant . Although lop away bear on arm can meliorate the plant ’s appearance , this disease has no discourse and will eventually destroy the oleander .
Oleander Knot
Oleander grayback causes knot - like growing with uneven surfaces on stem and branches . Affected stems might die back , but the entire plant usually survives . Remove affected root by pruning them off as soon as they come out , to avail prevent further spread of the trouble . Bacteria maturate in cuts in the plant life ’s bark and spread when water runs through affected areas . The disease also spreads on tools used to cut back flush or to prune away affected stems . you could help prevent this by cleaning puppet as you work , wiping them with alcohol or household blanching agent , but wear gloves to protect your skin . Also avoid overhead watering ; instead , use drip irrigation or a soaker hose to keep foliage dry and prevent bed cover of bacteria in contaminated water .
When cut an Nerium oleander , alwaysremove cutting from the area right away , even if there ’s no grounds of disease , to assist prevent fungal growth or spreading of any problem that ’s not obvious .
An oleander bush is susceptible to several different type of bacterial disease , each causing different symptoms .
Fungal Disorders
Leaf Spot Diseases
Several dissimilar types of fungi cause problems together with calledleaf spot diseases . As the name suggests , smirch appear on the plant ’s leaves , sometimes as yellow or brown patches that can be small or overcompensate a tumid part of the leaf . A austere problem might cause some leafage to fall ; if you see this happen , prune off affected branches by reduce into healthy wood behind the trouble country , disposing of cuttings as you work . keep foliation dry bywatering at the flora ’s basealso help control this problem , as does watering early on in the day so foliation dries quickly . take away industrial plant debrisfrom under the shrub regularly also helps prevent banquet of the fungus .
Sooty Mold
You might also see a blackish stratum on the plant ’s stems and impart that resemble soot — calledsooty modeling . The mold grows where insects that feed on the plant have deposited a sticky substance calledhoneydew . mould - coated leaf can slack the plant ’s increase and some leaf might eventually die . To verify jet clay sculpture , destroy the soft - bodied , sucking insects that deposition honeydew by spray the plant until it ’s dripping wet withinsecticidal soap , thin out at a rate of 5 tablespoon of water per gal of weewee , and duplicate every two weeks as needed .
An oleander bush might also develop one of several fungous disorders , each with its own stage set of identifiable symptom .
