Hi, I tried posting in the Citrus forum but it wouldn't let me start a new thread there,- so here I am. We have a Lemon Tree which looks very ill now and already lost lots of leaves. All the leaves became sticky and look like they are covered with oil. Leaves become dry, fold in and than fall off. Here are some pics. Any help is appreciated! Thank You!
The sticky substance on the foliage suggests the presence of a pest, possibly scale or aphid. However that would not explain the drying in the leaves which seems most prevalent in the lower portion of the tree. Is the tree exposed to a warm draft from a nearby heat register? As an aside, are you sure this is a lemon tree? The large winged petioles suggest otherwise.
Ok it does have bugs. We didn't realise it was bugs at first but here are some pics. Also it is away from warm draft - its in an apartment with radial heating and its not near the radiator. And yes we are pretty sure it is a lemon tree :)
It's confirmed - you have scale. Treat with either insecticidal soap or horticultural oil. With insecticidal soap the adults (the ones you can see) must first be physically removed before applying the spray which must be repeated after 10 days or so. I repeat the spray several times then stop and look for the telltale sign of minute specks of sticky honeydew. Repeat treatment if necessary. I haven't used horticultural oil before but it's supposed to be quite effective, more so than the soap. By the way, you should have made a new post for the new pictures and information instead of editing the previous one as that notifies other readers of a new entry in the thread.
