Why do vegetation get sick? The easy reply is for many causes, lots of them just like the the reason why we people do. Take, for instance, poor food plan. Just because it’s one of many root causes of illness, poor progress and decreased life expectancy in people, so it’s with vegetation.

That malnutrition could possibly be the results of a nutrient-poor soil or of overcrowding, the place there merely isn’t sufficient meals to maintain wholesome progress. Alternatively, it could possibly be due to sure rising circumstances equivalent to drought, a waterlogged soil, a compressed soil, or a really acidic or alkaline soil making it troublesome for a plant’s roots to simply entry key vitamins locked within the floor. Or it could possibly be due to a polluted soil that’s been contaminated by poisonous chemical substances.

Either manner, the result’s stunted and/or distorted, discoloured progress, decreased flowering and/or fruiting and a basic lack of vigour that then leaves it weak to pests and illness.

Just like people completely different vegetation additionally reply in several methods to the environments they discover themselves in. Ericaceous vegetation equivalent to azaleas, rhododendrons, camellias and a few species of magnolias, for instance, naturally thrive in a humid however well-drained acidic soil with a pH decrease than 7. But plant them in an alkaline soil they usually’ll rapidly develop a situation often called lime-induced chlorosis, the place their leaves flip yellow. This yellowing of the leaves is brought on by the truth that the alkaline soil during which they’re rising interferes with an ericaceous plant’s capacity to soak up key plant components, leading to an iron deficiency that’s the horticultural model of anaemia.

But that’s not all. In precisely the identical manner that dietary deficiencies within the human food plan have a cascade impact by way of our general well being, the dearth of chlorophyll (the pigment that usually makes leaves seem inexperienced) within the leaves of a chlorotic plant has different rather more severe penalties, chief of which is its incapability to photosynthesise. Robbed of that all-important capacity to soak up power from mild, it sometimes weakens and dies.

Similarly, different vegetation can change into unwell on account of cumulative stress brought on by inappropriate rising circumstances ill-suited to the actual species. Plant a heat-loving species of ornamental shrubs and small bushes equivalent to Californian lilac (ceanothus) that’s native to a lot hotter climes into a chilly, uncovered Irish backyard and it’ll endure to the purpose the place it grows weak and ultimately dies.

In the identical manner when you stick a shade-loving, spring-flowering woodland species right into a scorching, dry border it gained’t thanks for it. Nor will a drought-tolerant species of succulent or cactus that’s advanced over 1000’s of years to deal with excessive warmth and a dry soil, however as an alternative finds itself offered with a chilly, moist, poorly-drained web site. All of which is why seasoned gardeners all the time do their absolute best to comply with that age-old mantra of “the right plant for the right place”.

Even then container-grown vegetation specifically can endure from stress and unwell well being irrespective of how nicely located or appropriately chosen they’re for a backyard’s rising circumstances. This is as a result of their weak root techniques are way more uncovered to temperature extremes than if grown within the floor, whereas they’re additionally extra weak to the results of drought, wind and even waterlogging.

Unless the compost during which they’re rising is recurrently top-dressed and infrequently changed, container-grown vegetation are additionally way more prone to ultimately endure from malnutrition as soon as the plant has used up all of the out there vitamins contained inside the compost. Alternatively, they will endure from what’s often called “salt-burn” on account of a gradual accumulation of fertiliser residues within the compost. Add to this that their ever-questing root techniques will ultimately attain the perimeters of their containers, inflicting them to change into what’s often called “pot-bound” (the horticultural equal of us people strolling round in a pair of footwear a number of sizes too small for us) and it’s no small surprise that they’re typically sad.

[ The rewards – and challenges – of growing your own food ]

In this weakened, harassed malnourished, state these vegetation are additionally much less capable of struggle off many widespread species of sap-sucking and leaf-boring plant pests. This is why it’s common to see a nasty infestation of aphids thriving on a uncared for container-grown plant that’s been underwatered, or one which has change into pot-bound.

Just like people a plant’s age additionally impacts its general well being and talent to tolerate hectic circumstances. Young seedlings, for instance, will rapidly succumb to widespread plant stressors equivalent to a scarcity of water or sharp extremes of temperature whereas their mature equal is not going to.

If you’ve ever grown your personal summer time bedding vegetation then you’ll have skilled this on the freshly-germinated seedling stage – after they have to be rigorously cosseted and guarded towards low temperatures and chilly drafts if they’re to outlive – whereas later within the rising season the mature vegetation are an excellent deal extra resilient.

Likewise, younger comfortable vegetation raised below the protecting cowl of a polytunnel or glasshouse after which abruptly positioned open air to face the rigours of the Irish climate can even, fairly understandably, show widespread signs of stress, together with dropping their leaves (an excessive technique to preserve water and cut back the stress on their immature root techniques), curling of leaves (one other technique to preserve moisture) and dropping of flowers and flower buds (ditto).

At the other finish of the size very mature vegetation reaching the pure finish of their lifespan are additionally extra weak to pests and ailments.

Physical accidents to a plant on account of storm injury, poor pruning strategies or simply badly-timed pruning can all go away it way more weak to pests and ailments. Prune a pear tree in autumn or winter, for instance, and also you significantly enhance the probabilities of it falling prey to the harmful fungal illness often called “silver leaf”. But when you prune it in on a dry, brilliant summer time’s day when there are far fewer fungal spores about and the pruning wound is extra prone to rapidly heal over, you then significantly cut back the danger.

Likewise even comparatively small accidents to a plant on account of wind, hail or frost injury, clumsy strimming, grazing by animals, and even simply common chafing of an excessively tight tree-tie can enable entry to pests and ailments from which its robust bark or outer pores and skin of plant cells would in any other case defend it, very similar to a human struggling blood poisoning on account of by chance strolling on a rusty nail.

In quick, vegetation are surprisingly like individuals with regards to lots of the issues that make them unwell. But present them the identical consideration that you’d a good friend or cherished one they usually’re more likely to remain wholesome and completely happy.

This week within the backyard

• The first killing frost of autumn arrived in lots of Irish gardens final week, signalling the arrival of late autumn and the top of one other rising season.
• Now is the time to start out planting and planning for subsequent yr by planting bulbs in addition to many sorts of bushes, shrubs, perennials and climbers.
• Clear out summer time containers, place frost-tender perennials and shrubs below cowl, refresh the compost and replant with a mixture of hardy bedding, evergreen shrubs and spring-flowering bulbs.
• If you sowed seed of hardy annuals again in late summer-early August then it’s vital to get the younger vegetation within the floor as quickly as you may in order that they will get well-established earlier than the arrival of winter correct.
• Always put together the bottom nicely earlier than planting by eradicating weeds and dealing some well-rotted backyard compost or manure into the soil.
• Yung module-raised transplants can even profit from having their root ball soaked in an answer of liquid seaweed simply earlier than planting.

Dates to your diary

• October twenty sixth (8pm), Northridge House, St Luke’s, Castle Road, Mahon T12H970 Cork. “Spring Bulbs”, a lecture by Richard Hobbs of Witton Lane Seeds, Norwich, on behalf of Cork Alpine Hardy Plant Society, all welcome, admission €10
• From Sunday, October twenty ninth till Sunday, November twelfth National Botanic Gardens, Glasnevin, Dublin. “Crainn na hÉireann”, an exhibition of over 60 work produced over the past two years by members of the Irish Society of Botanical Artists as a celebration of the seasonal fantastic thing about Ireland’s native bushes, see irishbotanicalartists.ie