Question
QUESTION: My lemon tree is 3 years old, and it summers outdoors and I bring it in mid September.  This year the leaves began yellowing with slight green veins, before I brought it in.  I only water when he moisture meter reads dry so I feel comfortable that it's not being overwatered. I have special fertilizer that I use from the tree farm I bought it from, so I thought I was giving the proper balance of fertilizer and minerals. It had been a year and half since I repotted - I was afraid I might be having a soil problem so I repotted. 85% of the leaves had already dropped off (old growth) didn't bother new growth.  Now the new growth is falling off with the tips browning and the leaves look like they are beginning to yellow with the veins staying greener. I have the tree inside and I finally found a small dark bugs on the leaves I'm just wondering if these are mites and if this is why I was loosing leaves all along?  And what's the best way to treat. I am getting tiny new growth on the old branches but the leaves look deformed.  Thank you for any help you can offer.

ANSWER: Laina:
The yellowing leaves w/greer veins sounds very suspicious of a soil related problem.  This may likely be too much water. Carefully take a look at the roots from several spots from the root ball for a nice white/creamy color. If they are black and pull apart easily, then you may have a root rot- often associated with overly wet conditions for an extended period of time. I good rule of thumb when watering potted plants is.  First-Pour water into the pot for several minutes , allowing it to run out through the drain holes in the bottom of the pot also for a few minutes.  (This wets things down good and flushes out any salt buildup in the soil that can cause a burn on the foliage). No more water until the soil is obviously dry and crumbles- OR until the plant sarts to look a little wilted- then repeat the watering process.

For you tree, also see if the roots have filled up the pot- literally running out of soil and all you have in the pot is a thick/compact mass of roots. If so, these need to be thinned with some pruning.

The bugs you describe are probably not mites. Mites are very small and usually orange/yellow in color and usually on the underside of the leaf. You can also see some webbing in the leaf stalk/stem juntion area.

I think that the leaf drop and discoloration is due to a soil/root issue.

Regards
Steve

---------- FOLLOW-UP ----------

QUESTION: When I repotted, the roots were white/cream in color and no black roots at all nor was the pot root bound.  The soil is kept probably on the dry side most of the time, and I'm very careful when testing the soil for mositure just due to the fact that I live in Washington and I realize overwatering could be a big problem,  I did find small amount of webbing this morning so I still think it's mite related.  But I don't know if they were the original cause of leaf loss. I thought I might have a salt build up which was why I repotted to begin with but I never had any white film in the soil or around the edges.  I've looked at the bug with a magnafying glass and they appear to be brown but due scurry across the leaf like a spider - so I believe them to be mites, what would you recomment for mite treatment.  - Thank you,  Laina

Answer
Laina:
Mites can debilitate a plant if the numbers are large enough- causing the leaves to yellow.  Insecticidal Soap is a safe product to use for numerous insects and mites. Spray your plant outside, making sure the spray gets on both sides of the leaves. You can find this product at any garden center or nursery.  It comes in a ready to use spray container. One brand is Safer Brand Insecticidal Soap. For spider mites, some folks just spray the leaves with a high pressure spray of water to wash these critters off.
One method of detecting these spider mites is to tap a few suspected leaves over a white sheet of paper.  You should be able to see these tiny things crawling on that white background.

Salt levels can buildup in the soil before they show up on the pot surfaces. Just do the periodic "flush" to keep them from building up. You can also have a soil test done through your local Extension office and it is usually free. Check with your garden center/nursery about contacting the Extension office for that service.

Steve