Plant Doctor Archive

 MY lemon tree forks into two trunks just above the soil and for many years has grown normally and fruited well. Now the right-hand side of the tree has little foliage left while the other is growing normally. I can see no signs of borer. I apply fertiliser and copper and oil sprays regularly. Can you advise me?

  FROM your photos I suspect borer may be the problem, even though you haven’t seen any evidence. A borer close to the base of that side of the tree could cause these symptoms, so check carefully — you might find a small entry hole. If you do, try inserting a piece of fine wire into the hole in the hope that you might spear the borer. However, they can be very hard to get at and, as the damage is already done, it may be too late to save that side of the tree.

Damage to the roots on that side of the tree, caused by poor drainage or physical insult, may produce similar symptoms.

I recommend you remove all fruit from that side of the tree to reduce stress — given good conditions it may recover. However, if that side of the tree continues to deteriorate you may have to resort to removing it.

Weekend Gardener, Issue 206, 2006, Page 37

• The views expressed here are not necessarily those of the RNZIH
• Content or advice may be out-of-date.