Box blight is now one of two major problems for one of the most important hedging and topairy plants we have in the garden, the other being the box moth, that is causing a lot a problems in London at the moment. To the rest of us, blight is the biggest concern in the garden if we have box hedging or topiary, is that browning of the leave tips the start or just leaf scorch?
So what is box blight?
Well it is a fungus that causes problems to the stem and leaves of members of the Buxus family. It doesn’t effect the roots of the plants thankfully. There are two blights that effect the Buxus, first one is the main blight, Cylindrocladium buxicola and the second one is called Volutella blight, this one is a little less serous. The signs that your hedge maybe infected with Box Blight (Cylindrocladium) are first of all, small patches of dieback appearing on the hedge.
These little patches will soon spread and the dead woody growth waill have black streaks visible though the spilting bark. This can spread over the whole plant quickly. The tiny spores form under the leaves during wet mild spells, these are white. Volutella blight differs from not losing as much leaves, lack the black streaking and also have pink spores under the leaves instead of white. Box blight tend to spread by water splashes due to rain or over head watering, this can be wind blown as well. Like a lot of other foliage fungi, the younger leaves are much easier for the fungus to gain a foot hold and infect the plant. While Volutella blight, tends to be also spread on the open wounds after cutting. With Box blight, the spores can be viable on old dead leaves for up to 6years! One other warning is that Box blight isn’t just on Buxus but can effect other members of the Buxuacaea including Sarcococca,
So that’s the problem, so what about the effects on them, well it can be pretty bad with Box blight, whole sections of the hedging can die back, slowly spreading but again depends the weather and where the garden is based in the country, mild and damp really help the spread of the fungus, which does make it more at home in the damper areas areas of the uk. Volutella blight tends to cause smaller areas of dieback that can be cut out easily
However good the treatments can be, it’s far better and easier to prevent it in the first place. Some good methods can be used to both prevent it coming into the garden in the first place and also reducing the spread of it around the garden.
- First thing is selecting healthy disease free stock in the first place, try buying one or two plants to start with and place them away from other plants in quarantine for a couple of months to see if they develop the blight, many of the commercial sources of Box, do spray regularly as a preventive measure, so will be ok until this wears off.
- If you are looking at adding or replacing bits of existing Box hedging, topiary or indeed plants and your current stock is blight free, well worth propagating your own plants via hardwood cuttings to stop the disease coming in.
- If you are starting a new parterre, hedge or topiary, it’s well worth using Buxus microphylla hybrids like Faulkner, have been found to be less susceptible to both fungi compared to Buxus semperverens.
- Also try not to plant too close, increase the planting distance will help to reduce the density of the hedge.
- Once planted, box is a hungry and thirsty plant, something that we tend to forget, good feeding and ground level watering will help to keep plants stress free and growing them in a healthy soil again will keep them in better condition, a strong healthy plant is more able to fight pest and diseases it just also be careful not to overfeed as this can encourage the plant to put on lots of soft growth that’s also more susceptible to the fungus.
- Think about adding a soft mulch under the hedge, something like Progrow, compost and mushroom compost rather than bark mulch or stones, the soft mulches will reduce the height of water drop splash back onto the plant.
- Avoid watering the box using overhead watering systems, something like leaky pipe or drip irrigation is better and avoids water splashes.
- Good husbandry by clearing out all the dead leaves at the base of the hedge and also not blowing the leftover trimmings back under the hedge! While on the subject of using blowers, try to avoid the use of them when the hedge is wet from rain or heavy dew.
- Trimming is another job that’s pretty crucial in reducing both the risk of introducing and spreading the fungus, not only just from the trimming and the open cuts it’s produces but also from the fact that you encourage new softer growth, which being so soft, allows an easy way for the fungus to gain a hold.
- And also regular trimming encourages a very dense front to the plant, that is pretty difficult for sprays to penetrate. Traditionally the time to trim your box is late May but trimming at this time of the year tends to produce 2 lots of soft growth per year, one just before trimming and one after, changing the time to late summer/early autumn will only produce one lot of growth in the following year and therefore reducing the risk, yes it will look not as sharp in mid summer but if it cuts down the risk, it must be worth it.
- Also try and cut it on a dry day, once any early morning dew and rain has dried off from the foliage.
- Another big tip on cutting box, must be to ensure the equipment is clean, both sap being cleaned off the blades regularly with something like Niwaki’s cleam block to avoid build up.
- Also worth sterilising the blades using either something like white spirt on a cloth and wiping over the blade or my favourite method of using bleach, either in 5% solution in a bucket so you can dip the hand tools into the mixture every few minutes or every time you move on to another plant or section of hedge. Powered equipment can be easily treated using bleach in a spray bottle and sprayed on the blades as per hand tool use. This is well worth asking and making sure your contractor does this if you are using one!
- One other tip to do 7-10 days before trimming the box, is to spray with a fungicide (see later on for recommend ones) and then repeat 7-10 days after, this again will help on reducing the spread of the fungus and checking the establishment on newly cut areas. Just one more reminder not to blow the trimmings under the hedge after you have finished! Indeed, never be afraid to tell you contractor that as well!
- One last tip on prevention, think about maybe starting up a regular foliage feed spraying of the box to feed the leaves and make them stronger, again stronger healthy leaves are much better at fighting dieseases, products like Uncle Toms Plant Tonic, that helps to encourage tougher new growth, liquid seasweed, that adds lots of trace minerals as well as a general feed, Topbuxus is also a great produce to spray every 2-6 weeks (depending on product) during the season.
Management if you already have it
Well with most fungi problems, you would have the cure of the disease here, but there is no cure for Box blight just management of the fungus. If it’s already in the garden, most the information above will help to slow down the movement but the diseased plants need a bit of treatment, this varies depending on how bad it is.
Beginning of an infection can be treated by removing diseased material and burning it, then clearing away old dead leaves, then start regularly foliage spraying as per prevention and also using some of the fungicides that are now on the market for domestic use including Bayer Fungus Fighter that can be sprayed 6 times a year. Professionals will have access to chemicals like Signum, Bravo 500, Switch and Amistar
A severe infection needs a little bit more work, all dead branches need to be removed, indeed it maybe worth renovating the section, cutting main branches back to the stem on half the plant, encouraging new healthy growth to come though and allow better access to both remove old dead foliage, adding mulch to the plant and allow the chemical/liquid feed to penetrate all areas of the plant easy. Once it started to regrow nicely, then that’s the time to cut back the other half. It is then a case of carrying out the preventive advice above on the box for the life of the hedge
Yes admittly it’s a lot of work to keep a plant in the garden, but if you are keen and want the best from what’s growing in the garden. There are always a few alternatives to plant instead of buxus, plants like Taxus can make a good choice if another tight sharp looking hedge is required, but to be honest, there’s nothing that looks as good as a box parterre or edging. If you want that look, it’s just worth taking the time to either keeping your ones safe or managing the problem. The days of planting and forgetting are now sadly gone but maybe we shouldn’t of done the ‘plant and forget it’ in the first place, we dont tend to do this for all the other plants in our gardens do we? so why our hedges and topiary, the important framework of our borders.