Yew Hedge Problems

richardvickers10

We remodelled our front south facing garden two years ago (autumn 2017), taking out a large birch tree that was sucking all the moisture out of the soil and preventing a yew hedge that was planted in 2009 and other plants from establishing. We replanted a section of the hedge where the birch was and covered the whole area with two inches of gravel over a geotextile membrane.

The following summer (2018) one isolated yew died quite suddenly which I put down to bad luck. Then a row of five plants died which I attributed to vine weevil as we had problems in the past. So I treated the soil with a nematode and also the replacement plants whilst still in the pots. I planted the replacement yews this spring (2019) and kept a close eye on them, watering during dry periods. However, at the start of this month (September) two of the yews that were planted in the autumn of 2017 started to die back and now look quite sickly and the replacements that I planted in the spring of this year are a much lighter green colour than when planted.

I've ruled out vine weevil as the likely culprit as none of the yew plants exhibit distinctive notches in the leaves, plus the adults would have to burrow through two inches of gravel and a membrane in order to lay their eggs. I also don't think its a case of too much or too little water. From research online, honey fungus is a possibility although yew plants are supposedly quite resistant. I've pulled back the gravel and lifted the membrane around the two most sickly plants and can't see signs of the distinctive white fungus around the base of the stems, but I can see apparently healthy roots although I'm no expert. Also when I scratch the stems in places the wood beneath is quite green and healthy looking.

So I am at a loss to explain why the replacement yews keep dying off. In addition, one of the yews in the established section of hedge planted in 2009 has also started to turn a bright green-yellow colour with brown bits.

Can anyone help?

Borderline

I'm assuming that membrane allows water to pass through. If not, then it's definitely a water issue. From what you describe, it's very likely your plants are not getting enough water. Young shrubs need regular deep watering, especially in the warmer months. Gravel may look good, but not ideal for young plants trying to establish.

If the photo is taken now, then your plants are struggling. They should be more bulkier by now. Have they been pruned them back since 2017? Yearly pruning will also help your plants to branch out more, making them more dense.

JennyJ

Did you improve the soil before they were planted? The birch tree will have taken all the goodness out of it in the area where its roots were. Also, they look quite close together so they're probably competing with each other for moisture and nutrients. A good organic mulch instead of membrane and gravel would probably be good for them (but migh not fit the look that you want).

richardvickers10

Thanks Borderline/JennyJ for your comments. The membrane is a geotextile membrane, not plastic, so water passes through and we did work in some compost to the trench when we planted the yews but possibly not enough. The photo was taken yesterday - the darker green plants (to the right and one in the centre) are the ones that were planted in Autumn 2017 and have survived so far. The smaller and paler green plants (centre) are the ones I planted this spring. The two most sickly plants were planted in 2017. None have been pruned to date.

If lack of water is the problem, then I will leave them and monitor them over the winter/spring. We had rain of biblical proportions overnight, so they've had a good soaking!

Obelixx

The water needs to go down deep and if your soil was dry even a biblical downpour won't have penetrated far.   Keep an eye on rainfall and if you don't get more then water them well because now is when roots like to do some growing underground, out of sight, to prepare for the spring growth spurt while the top stuff is relatively dormant and not making demands.  If the roots don't develop over winter your plants will struggle again thru spring and summer.

richardvickers10

Will do - Thanks again

richardvickers10

Hi, I raised the above problem with my yew hedge this time last year so I won't repeat it all again here. At the time, the consensus of opinion was lack of water which was causing the plants to fail. One year on, and despite a particularly wet winter and regular watering and occasional feeding with liquid seaweed during the summer, my now two year old plants are continuing to die back. Also, one of the three year old plants has browned off in the last couple of months. I've attached some photos taken today to illustrate the problem.

I suspect it is something in the soil that is attacking the roots but don't know what (I've ruled out vine weevil). So I'm tempted to dig up all the plants and leave fallow for a year to hopefully kill off anything this is causing the damage.

Does anyone have any other ideas?