I have an orange tree which is producing only small fruit, can you give me some advice on what is going on with the tree ?. Thanks, Andy, Sydney.
Orange trees can produce small fruit for a number of reasons. Generally you find that "Valencia" orange trees tend to hang on to their fruit, even when the tree is under stress, so I think it could be a "Valencia". "Washington Navel" is the other popular variety, but it tends to drop fruit, "self thinning" when under stress and still produces some large fruit (although less of them) under most conditions.
Generally speaking citrus produce small fruit for the following reasons:
1. The tree has produced masses of fruit which has "set" and is developing. This means that the tree spreads it's effort over all the fruit, feeding every single one. The result is that the tree can only give so much, so each fruit is small.
2. The tree is not getting enough water during the period of the fruit developing. The fruit has "set" then the tree has not been able to feed the fruit due to water stress. Make sure you water the whole root zone during the period after the tree has flowered. This will allow the tree to feed moisture to the fruit. I would suggest you use some hose on wetting agents and Seasol to help moisture holding and penetration. Also, use a citrus fertiliser. There are fertilisers made specifically for citrus.
3. In very sandy soils, where there are little in the way of nutrients available, the tree will produce, small pale fruit.
4. Some diseases can create small fruit, but I think this is unlikely.