The following is a report prepared by Kevin Quinlan, Supply Chain Manager for MPC based on a presentation given by Matthew Moyle, Nufarm Territory manager for Northern NSW.
Growers have used Lepidex® for the control of flower caterpillar and reported that the results have been poor. This is believed to be as a result of alkaline hydrolysis. Alkaline hydrolysis causes certain chemicals to breakdown rapidly when they are subjected to high pH conditions.
For example, adding Lepidex® to water at a pH of 8 will cause 50% of the product to breakdown in 63 minutes. This means that the chemical concentration is less than what is needed to give good control. To overcome this problem a product such as LI700® can be added to the tank solution. This product buffers the pH and reduces the breakdown. It is a good idea to test the pH of the water you wish to use for spraying to determine whether or not you need to add a buffering solution like LI700®. Like all other sprays, coverage is crucial for the best results with Lepidex®.
If the pH of your water is low or you add a buffer to reduce the pH, then adding copper based products has been found to cause phtyotoxicity problems in some crops. Research work is being undertaken to test whether macadamias are susceptible to this problem. As a result it is best not to add copper to a tank solution that has been buffered to reduce the pH until this research work has been completed.