We use cookies to improve your experience on this website. Read More Allow Cookies ×

December '14 - Merry White Fly

December '14 - Merry White Fly

The festive season is upon us and white fly are starting to party early!! Growers will start to see a large increase in pest numbers and it appears that they are becoming increasingly hard to control. An increase in white fly potentially means that Psyllid populations could be on the rise. For the past two seasons Psyllid has been a real problem. Especially in February and March, during the droughts, but that does not mean grower's can relax this early in the summer season.

The white fly is either becoming resistant to traditional control methods or the natural population outside are higher than normal. I've had satisfactory control this year, spraying using a combination of chemistry and friendly products. The white fly population is growing so I need to keep on top of them. I'm using a programme, which has worked for me in the past, but my concern is what to replace it with when it no longer works? I will be trialling a new product, on a small area, to see if it could be another tool to add to the arsenal. There are a lot of products that help contain white fly, but in my experience there is no magic solution that will give total control. To view the products I use to control the white fly and other control suggestions log in to grower2grower.co.nz and read the December Technical Article section.

Good application when spraying is very important, the type of spraying system/ setup you have will determine the degree of success at hitting the target. I find that there are several important components when applying sprays;

The distance between nozzles in your spray boom should not be too large.

The type of nozzle that you use is also important. Some experts say a cone nozzle and some a fan nozzle. I like to use a .3mm fan nozzle. For me this has worked best over the years - I can only go from experience.

Mixing your sprays correctly is really important. For example I mix one product with warm water to help it diffuse better in the main tank. Check with your supplier what the recommended PH in your spray tank should be. 

The pressure you spray with and the speed you travel are extremely important. For example I work on the principal of using 2000 litres per hectare if spraying the full canopy of the crop. This means 4-5 nozzles on each side of the spray boom. I have found if the pressure is too high then I will have to travel too fast to apply the spray effectively. I move at a normal walking speed. Spraying should not be rushed. I like to see the leaf flick up and the spray go underneath the canopy. This applies for both insects and funguses etc.

My advice is to slow down and apply the products so that you have good contact on your target. Spraying is an important part of our growing activity and unless we have full biological control systems then we must learn to improve applying spray.

Best wishes to all for the festive season, eat well but not too well so you can still fit into your spray suit, I mean Santa suit!! 

Additional Information for Grower2Grower online readers


Over the past two seasons I have used a combination of chemicals and Eco-oil to control my whitefly. I will often mix different chemicals together to try and kill both adults and the early stages of the whitefly life cycle.

I have used Oberon, Avid, Eco-oil and Admiral plus a small amount of Neem AQ over the past two seasons. 

  1. Oberon is one chemical group I will not mix with anything else. Other growers do but I just think the risk is too big. I always apply Oberon as early as I can in the morning in the cooler months or late in the afternoon in the warmer months. The trick is to do two applications one week apart and use this product when adult white fly numbers are below 5 per plant (Full canopy spray)
  2. When whitefly number increase or you start seeing Psyllid damage then the use of Eco-oil, Avid.  Both are used to control these pests. The combination of these will have a good knock down. I would apply this combination twice over a three week period. (Top two thirds of the plant)
  3. I will then follow up two Admiral sprays one week apart. (Full canopy spray)
  4. Neem AQ was used two weeks after the Admiral at one week intervals for four weeks, with the target only being the top third of the plant.

The chemicals above have given me good control over the past two seasons. The key is to not let the adult numbers get too high. Once they are too high then it is very hard to control them even with all of the sprays I have used. For me it has worked and with the use of Neem AQ towards the tail of the crop. Last season I did not have to spray my crop for the last 8 weeks it was in the greenhouse. Considering that these two months were December and January made it even more impressive. This year is a different story; I will have to spray this week for whitefly as the numbers have built in the past three weeks.

Growers are concerned that the chemicals available to us are not having the effect of previous years. This is a major concern for our industry if this is the case. Organic products are good but how much plants can tolerate is another thing. 

Tip: Use sticky traps especially at the start of the season. I have always found that sticky traps on trolleys work well and will catch a lot of insects. When the pressure is too high then sticky traps will still catch insects but only not enough by themselves.

If you want to discuss the rates of the different chemicals and Eco-oil suggested then send me a message and l will try and tailor a programme suited to your situation and planting date. You must be a signed up member to receive this help. Remember it is free to sign up and all advice will be given free of charge to commercial growers.

Merry Christmas, to all of the hard working growers. The last two months have been difficult for growers with low prices and high insect and disease pressure. But no one is doing it as tough as one of our fellow growers who is fighting cancer. I wish him and his family all the best for the festive season and to a speedy recovery. I have been missing our catch ups and debates over the ‘little red miracle’ so hurry up and get better mate.