Welcome to the first IPM Practitioner.
This is a series of articles about practical IPM—the IPM carried out by orchardists and advisors—those of us walking the crops monitoring and seeing what is out there and advising on pest, disease and weed control.
To start, an explanation of IPM, where it fits and what it does.
What is IPM?
"Integrated Pest Management (IPM) is an effective and environmentally sensitive approach to pest management that relies on a combination of common-sense practices.
IPM programs use current, comprehensive information on the life cycles of pests and their interaction with the environment. This information, in combination with available pest control methods, is used to manage pest damage by the most economical means, and with the least possible hazard to people, property, and the environment.
IPM takes advantage of all appropriate pest management options.
Including, but not limited to, the judicious use of pesticides."
This definition, from the USA EPA, is the most practical, and sums up the realistic aspects of growing fruit.
An addition to the USA EPA definition above is to view IPM as a management practice, and the management tools are the pesticides, parasites, predators, crop management, weeds, etc.—everything that influences the growing of the crop.
So, to the first IPM challenge: Longtailed Mealybug.
In the Murray Valley and Goulbourn Valley fruit areas, Longtailed Mealybug started to increase last season, but have exploded this season.
Quick facts: Pseudococcus longispinus (Longtailed Mealybug)
- First recorded on grapevines in Western Australia in 1898.
- It is an Australian native, although other Mealybug around the world is also known as Longtailed Mealybug.
- Depending on the area, have 3 to 4 generations per year.
- As a pest we have exported Pseudococcus longispinus (Longtailed Mealybug) to Hawaii, New Zealand, UK, and California.
- There are seven native natural enemies, mostly parasitic wasps and ladybirds.
- Major parasite in temperate fruit is the Mealybug wasp Tetracnemoidea sydneyensis.
- The ladybird Cryptolaemus montrouzieri is also known as a major predator.
Why a major pest?
The key question is why the Longtailed Mealybug has developed again to be a major pest, especially in pears, but also finding it in apples, plums, pluots, persimmons and peaches.
Some 10–15 years ago it was a major problem, but new chemicals released during that time have given control.
This is a hard question, with no ready answer. There does not seem to be a significant change in chemical programs in the last two years, to implicate a particular chemical for the reason.
We suspect that two chemical products may have a significant effect on the parasitic wasps. These insecticides are used for Codling moth control. But there are orchards that have not used these products, and still have large Mealybug populations.
Weather
The short answer maybe the weather.
A change in weather since the drought (this is only the second season) has either had a favourable advantage for the Mealybug, or an unfavourable climate for the natural predators and parasites.
With any IPM system, there is the predator/prey cycle where the prey (or pest) increases but there is a time lag for the predator to breed and control the prey (or pest).
Our challenge is to find why the Mealybug is increasing and the natural enemies have not caught up. Possibly this may have been happening for more than the last two years, and we are only seeing the Mealybug population build-up now.
Monitoring
We are working though this Mealybug situation.
At present we are harvesting pears and this will give an indication of the level of fruit infestation and how big the problem is.
Monitoring the level of parasitism by the parasitic wasps over the winter will give an indication of level of control by the good bugs.
A major consideration for Mealybug control is monitoring the pest. In the spring monitoring for emergence for chemical spray timing or release of predators.
Continued monitoring for how well these control tools worked is the key to knowing if Mealybug are increasing and if more controls are needed, or not needed.
We have a trial block of pears where the Cryptolaemus have been released in the spring, and will report on the findings when we do the harvest assessment.
For information, images and contact details, see the February 2012 Tree Fruit.
