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Equals increase pest pressure
Whilst out visiting customers, or during on line consultations, it is pleasing to see that insect pressure is under control. However, I do have some Australian customers reporting an increase in whitefly numbers. One grower, I recently visited, hardly had a single whitefly and was still having good control with Encarsia. It was great to see such a fantastic crop set up perfectly for the summer. It helped the crop was strong, had a wonderful root system and was not burdened with too many fruits per m2.
Not to be pessimistic but this can change very quickly. Psyllid yellows were an issue last summer and I don’t expect this issue to have disappeared. Also, other growers have expressed concern over increased pest numbers. For smaller businesses, with no green bridge (multiple crops on the same site with different planting dates), it is much easier to control insect pressure if you start the crop clean. It is also very evident the longer you have a zero tolerance to whitefly the longer you will sleep well at night. However, I fully expect large plumes of whitefly to begin hatching outside and finding its way to greenhouse crops, psyllids may be on the heels of the whitefly so it is very important that businesses pivot quickly when necessary.
This is what can happen in less than two months if you ignore whitefly
With now being the busy time of the year, it is a reminder not to take the foot off the throat of the insects. Easier said than done but an important message.
Integrated Pest Management is a great tool to avoid spraying. To stay in control using beneficials at this time of the year you may need to either increase the numbers of beneficial insects or have a threshold for when you will require alternative interventions. If you want to keep using beneficials, for as long as possible, then consider spraying with products that have limited mortality on the beneficial product you are using. Specifically ask if the product you want to spray is compatible with the exact beneficial insect you are introducing. Some products could be less harmful than others so you need to check with your supplier. Any time you spray it will have a negative effect on beneficials, limit your spraying and make sure you spray before you introduce new beneficials, especially if you are using oils or natural products. Try and give your beneficials a chance.
It is hard observing black scale on the underside of lower leaves because the black scale/parasitisation occurred weeks earlier and may not be representative of the present. Sticky traps on trolleys or around entrance ways are a great way to monitor pest pressure. For example, if a row is 100 metres in length, by the time I had worked on that row if the sticky trap was bursting with whitefly, I knew I was too late and had a big issue. If there are a hundred insects then you can quickly work out in around two weeks you will have a much larger issue on your hands.
Sticky traps close to entrances and on high trolleys act as great indicators of pest build up.
Insects are only going to increase, with an uncertain summer price making sure you have a clean crop could give you a distinctive advantage – and make it easier to sleep at night.