|My dwarf lemon tree, grown in a tub has hard whitish fruit.
what am I doing wrong ?
|Without seeing the fruit, I'd venture that the problem is cultural and due to wide fluctuations in soil moisture during the development of the fruit. There's an off-chance that the problem is caused by the Citrus Peel Miner (Marmara salictella Clemens). Eggs are deposited singly on the stem or more preferably citrus peel and hatch in about 5 days. The eggs are very small, oval in shape and convex on top. They are whitish in color and the top has some indistinct sculpturing. The number of eggs produced per female moth is not certain, but some have laid 7 to 12 eggs over a 4-day period.
The larvae exit the egg from the bottom and immediately burrow into epidermal layer of the peel. Thus they are never exposed. The larvae will extensively mine the peel of the fruit while passing through 6 instars. The 6th instar cuts out of the mine and lowers itself via a silken thread, to the ground or niche on the tree to pupate. The larvae complete their development cycle in 20-28 days.
You might want to further inspect the affected lemons to see if you can find tunneling between the rind and the pulp of the peel.
Here are some general guidelines for care:
Citrus trees adapt well to growing in containers. During the growing season, keep them evenly moist but not sopping wet and provide them with plenty of sunshine. Fertilize according to the label instructions with a fertilizer containing micronutrients (particularly zinc, iron and manganese) as well as the usual nitrogen, phosphorus and potassium found in complete fertilizers. During the winter, reduce the watering somewhat when they slow their growth.