Wind burn 03/05/08

The chilli plants have grown real tall now, so tall infact that the upper leaves are in the direct pathway of one of the circulatory fans at the top of the greenhouse. The force of the air movement causes an extreme case of evaporation of water from the leaves. Transpirational pull cannot keep up with the moisture loss and so cells in the leaf dry out. At such a level of water evaporation from the leaves it leaves behind the nutrient salts that cannot evaporate making them more and more concentrated until they reach a toxicity level.
Leaf burn usually starts with signs of upward curling of leaves. Then there are similar signs to nutrient burn with browning patches and around the edges of the leaf, deformed growth patterns. To stop further wind burn effects i am going to move the fan to another area of the greenhouse. To prevent anything like this happeneing predict the growth of your plants when deciding on positioning of a fan.

Aphid pest problem 12/04/08

I have noticed some curling and deformities in the new growth leaves of the chilli plants. These deformities have come from toxins in aphid saliva that cause mutations of plant cells, they cells around these mutated cells grow and expand, resulting in a curling effect.

When the leaf matures it fully expands and flattens out, where the mutated cells were there is now a hole because the imbalance of growth hormones of these cells don't allow the cells to form properly.






I have seen a few aphids on the lower leaves of a few chilli plants. This is not usually a problem as we release parasitoid wasps as a control regime for preventative measures.

A few aphids soon became a load of aphids, aphids are asexual this means they don't posess male or female sex organs. Infact they are born pregnant with an exact clone of themselves. You can tell which ones are mature and are ready to give birth by their size. A population of aphids can grow at an alarming rate. Our prevntative measures do not seem to be working.

Under closer observation i was able to identify the species of aphid as a glasshouse-potato aphid, they have long legs and the mix of parasitoid wasp that we were releasing were ineffective at ovipositing their young into the aphid. I ordered the correct parasitoid wasp, opened the bottle in the room and gently tapped it releasing the wasps around the plants. I noticed a difference within days.

The parasitoid wasp injects (oviposits) its fertilized eggs into the aphid which will live inside the aphid in its larval stage and will emerge from the host aphid as an adult. The aphid dies but its body remains intact but in a mummified form which is a pale colour.