Herself’s Houston Garden

While I’d heard a fair bit about leaf miners my first run in with them came this fall on the tomatoes I planted.  You can easily identify the damage.  It looks like someone took a beige marker and drew a squiggly line all over several leaves.  They are especially fond of vegetable crops.

Leaf miners are actually fly larvea.  The feed between the top and bottom of your plant leaves on the inside of the leaf.  As you can imagine this makes it very difficult to do anything about them.

In all but extreme cases they do little damage to the crop and are not something to be overly concerned about.

leaf miner damage

One of the most fascinating things about plant and insect evolution is the defenses they mount to protect themselves from prey. Often plants or insects become toxic to the critters that eat them. Sometimes they grow to look like closely related toxic plants.

Milkweed has taken a different approach. It grows faster to better feed the caterpillars. This is great news for us monarch lovers. Monarchs have evolved to resist the toxins in milkweed. Tracing milkweed back it appears milkweed has given up on growing better hairs and more toxic latex and decided to concentrate on faster growth and repair.

The adage that your enemies know your weaknesses best is especially true in the case of plants and predators that have co-evolved: As the predators evolve new strategies for attack, plants counter with their own unique defenses.

Milkweed is the latest example of this response, according to Cornell research suggesting that plant may be shifting away from elaborate defenses against specialized caterpillars toward a more energy-efficient approach. Genetic analysis reveals an evolutionary trend for milkweed plants away from resisting predators to putting more effort into repairing themselves faster than caterpillars — particularly the monarch butterfly caterpillar — can eat them. . . . [ read more Milkweed's evolutionary approach to caterpillars: Counter appetite with fast repair]

So far down here in Houston, aphids have only been a problem with the tea roses and not very often there.  When I find them I spray with orange oil ( you can find it with the organic pesticides at any nursery ).  A couple of days of treating with oil generally takes care of even the worst aphid problem for me.

Mercer recommends just giving them a good blast of water with your garden hose in the afternoon.  This removes them from the plant and they rapidly dry out in our afternoon heat.

Aphids are amazingly tiny and damage your plant by sucking all the fluid out of the plant.  Aphids are rapid multipliers.  They are all born female and pregnant. Aphids come in green, white, black and yellow.  But green is by far the most common color.

You will often find ants on plants with aphids. The ants come for the sap the aphids leave on the plant stems and eat the aphids.  The ants don’t hurt the plant.  Some ants will also treat the aphids like cattle, keeping them alive, moving them to healthier plants, and generally watching out for them so they may get more of the sticky sap.

Aphid damage often shows in malformed flower blooms or curled leaves and wilting of new stems and young plants.

If you’re a fan of habañero salsa or like to order Thai food spiced to five stars, you owe a lot to bugs, both the crawling kind and ones you can see only with a microscope. New research shows they are the ones responsible for the heat in chili peppers.

The spiciness is a defense mechanism that some peppers develop to suppress a microbial fungus that invades through punctures made in the outer skin by insects. The fungus, from a large genus called Fusarium, destroys the plant’s seeds before they can be eaten by birds and widely distributed.

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However, the researchers found that the pungency, or heat, in hot chilies acts as a unique defense mechanism. The pungency comes from capsaicinoids, the same chemicals that protect them from fungal attack by dramatically slowing microbial growth.

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[read more Bugs put the heat in chili peppers]

Another thing to remember if you want your peppers hot, is to go easy on the water. You want to keep the plant from wilting or being unhappy, but no more than that.