It is 2 feet tall, has been grown from a very small seedling in a container and is about 4 years old - located in southern California.
This article should help: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
Should I continue fertilizing guava tree with immature fruit on it?
This article should help answer your question: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
I planted a Guava sapling five months back. It has now grown about 4 feet tall and is healthy. What I need to know is when will it start to sprout out branches? (It is only growing straight upwards) Someone told me that I should cut the top off the plant and then it will start to grow branches. Please kindly advise.
oops, If you want a taller plant, don't take the growing tip now. If you prefer a shrubby plant to a tree, remove the growing tip now. The ultimate size and habit will depend on the variety.
These articles should help: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
https://aggie-horticulture.tamu.edu/citrus/guava.htm
http://forums.gardenweb.com/forums/load/tropical/msg0912364130164.html
Just want to know if you can make jelly from Asian Guavas because they never seem to turn yellow unless you wait a long time and then they seem to rot.
There are many types (and colors) of guava. The only reference to Asian guava I found said they were white inside, so you may be leaving yours on the tree too long. Or it may be a type that's just not as sweet as you had hoped. Here's an article on guava growing: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
That being said, of course you can make jelly from guava. And candy, and many other things. Here's a link to just one of the dozens of guava recipe site you can find online: http://www.tfgsf.com/?page_id=552
My tree had tons of blooms and made no fruit.
Plants that flower but do not fruit typically are having a problem either with maturity - guavas for example need to be 4 or 5 years old to fruit - or lack of pollinators. You can try hand pollinating, or plant other things that will attract more bees. These articles might be useful: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
https://www.gardeningknowhow.com/garden-how-to/beneficial/attracting-bees.htm
https://www.gardeningknowhow.com/garden-how-to/beneficial/insect-pollination-process.htm
My tree is a little over than a year old. I planted in March of last year and it bore fruit for the first time on or near October; just a couple, though. Now the tree is full of fruit but before they ripen, some are turning black and drying up. I also noticed a lot of ants up and down the trunk.
It sounds like your tree might have a fungus that affects as many as half the guavas in Puerto Rico. Unfortunately, there is no cure. The best treatment is optimum cultural practices, so your tree will be healthy enough to ward off disease and pests, remove and destroy any fruits or leaves as soon as they show a sign of disease. Also, your tree is very young, so do not stress it by leaving it full of flowers and fruit. The best idea is to remove at least 1/2 the flowers before they are pollinated, and then remove 1/2 the fruit that sets. This way, the tree has energy left to devote to growing roots and leaves, and developing its defense systems. Here is an article that will help you grow a healthy guava: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm
You might get in touch with the University of Puerto Rico Dept of Horticulture for more information.
It is October and has been a drought year.
Generally speaking, when a tree drops its fruit, it's because it doesn't have the energy to hold it; meaning, some kind of environmental stress or disease is affecting your tree. If you have eliminated bugs or disease (inspect the tree carefully, look for discolorations on leaves and bark, look for spots etc on fruit) look to moisture and nutrition. If it's been a dry year, have you provided supplemental irrigation in sufficient quantity? This article should help you with the basics of guava care: https://www.gardeningknowhow.com/edible/fruits/guava/growing-guava-fruit-trees.htm