Questions for Avocado
Our recommendations, and the recommendations of New Zealand Avocado, have been worked out over many years, taking into consideration the cost of monitoring to the orchardist versus the loss from insect damage. Those who monitor according to recommendations are regularly achieving packout’s of 85-95% with little or no insect damage. Those who choose to try and save money and not monitor are achieving a packout of 40-60% with insect damage of 40-60%. If you add up the average cost of monitoring of $1,000 – $1,500 per year and 3-4 sprays per year (because they are timed properly), the cost is little to achieve a payout that is worth having. Lets look at some figures.
If you have an orchard with 100 trees producing 1 bin of fruit per tree that is paying $1,000 (orchard gate price), that equals $100,000 per year. Now take off the cost of monitoring which equals 1 to 1.5 bins of fruit and the cost of spraying at say 2 bins of fruit. Then take off the cost of insect damage, maybe half a bin of fruit (if sprays went on at the right time), you now have 96 bins of export quality fruit left and $96,000 in the bank.
Now if you try and save on monitoring, you will probably have to spray 1-2 extra sprays to get on top of insect infestations, at a cost of $500 plus per spray. That $500 would have paid for nearly 6 months monitoring. From the 100 bins of fruit, take off 40 bins of insect damaged fruit, less the cost of 2 extra sprays, which equals 3 bins of fruit instead of 2. Plus a saving of .5 bin of fruit from less monitoring costs. Your total payout will be for 57.5 bins of fruit – $57,500 in the bank.
In short, saving on monitoring is no saving.
Note: this is an example only and does not include other on-orchard costs.
Pest Threshold Levels are set low to avoid as much insect damage to the fruit as possible. The ideal is to get your fruit to market with little or no insect damage.
A pest monitoring showing pest levels at or above threshold gives the grower justification to spray.
Some insects, particularly Greenhouse Thrip and Six spotted mite, can increase in number very rapidly. Therefore the thresholds have been deliberately set low under the AvoGreen© protocol, so sprays can be applied at the earliest opportunity.
Greenhouse Thrip can create large areas of blemish in a very short time. Where Greenhouse Thrip thresholds have been exceeded and no spray has been applied, AvoGreen© best practice requires us to monitor again in 7-10 days. Once you are over the 2% threshold, it is recommended that 2 sprays are applied within 21 days, to deal with newly-hatched Thrip eggs. Thrip can be a recurring problem from mid January until the end of April and often into May.
Even where fruit are not touching, small caterpillars can be found under webbing on the stem end of fruit. A great deal of damage can occur between one monitoring round and the next. We strongly urge growers to maintain a fortnightly monitoring routine, even when a spray has been applied, as the pests multiply rapidly in warm conditions.
Most insects are less active over winter, but are still there with the exception of Six spotted mite. They like conditions that are a little cooler and tend to increase through the Winter/Spring months, especially if there are low numbers of predators left following Autumn sprays for Thrip.
Six spotted mite feed on the leaves on the trees and can cause leafdrop, which affects the health of the tree for up to 3 years. Leafdrop can occur at any time of year but mostly from late Autumn till early Summer and is associated with high stress levels on the trees, such as dry weather, flowering, heavy fruit load.
It is highly recommended that you monitor 3-4 weekly through the winter months to monitor the Six spotted mite numbers, as well as Leafroller and Thrip, which can both still damage fruit over winter.
Questions for Blueberry
Blueberries have been grown in New Zealand for many years and have been accepted as a crop that does not need any pest management. As export markets have been developed, our Blueberries have been rejected because of pest incursions. As New Zealand Blueberries were thought to have no insect problems, growers have been struggling to increase their knowledge and to develop a protocol so we can continue to develop markets for our fruit.
Blueberries were traditionally grown in North America, but have now become very popular across the world. In New Zealand, Plant and Food Research have spent many years working on developing plants that are suitable for our unique conditions with different varieties having different levels of resistance to pests and diseases and therefore needing different methods of control.
As the export market developed, a couple of growers got together and worked out a basic protocol. This protocol was in place till the Blueberry NZ Conference in 2022, where a group of industry personnel were brought together to work out a better, more structured Integrated Pest Management (IPM) protocol to help us gain better access to markets, particularly Australia. This protocol is now being used by those that are carrying out monitoring for pests and diseases. IPM programs work to include a combination of methods in controlling pests and diseases in Blueberry crops which can include conventional sprays, organic sprays, pheromones, coloured tape, beneficial plants and beneficial insects.
As the Blueberry industry develops further, incursions of insects on our berries going into export markets has to stop or we risk being banned from export markets. For you as a growers, this means you need to be more proactive in your IPM program and monitoring is a key part of that program. For more information about monitoring your berries, contact us by email or phone from any part of New Zealand and we will come and visit or advise you on services available in your area.
Questions for Citrus
No thresholds have been set which leaves the decision up to the grower as to whether to take action or not, and when any action needs to be taken. We can advise on the insect life cycle but not the sprays that should be applied. There are other more qualified advisers available to give that advice like Farmlands or advisers at Citrus New Zealand https://www.citrus.co.nz/.
There is no IPM programme in place for citrus at this stage however, monitoring is good when done regularly to avoid pest and disease damage to the fruit and trees. It is advisable to monitor 2 weekly from October to April and 4 weekly monitoring from May to September.
1. Kelly’s Citrus Thrip
This insect does most of the damage at the end of flowering, mostly November/December. It is important to find the KCT just before petal drop, so the spray can be ready to go when full petal drop has occurred. Damage occurs possibly as early as when the flowers are starting to drop. Monitoring is recommended 2 weekly till spraying occurs.
2. Black Citrus Aphid
Black citrus aphid cause the new shoots on the trees to deform and can also be a minor cause of sooty mould. The BCA attract ants that love to ‘farm’ and ‘milk’ the aphid.
3. Citrus White Fly
CWF was first seen in New Zealand in 2006 and has now become widely established in our citrus, causing severe sooty mould on both the fruit and the leaves. A predator ladybird, the Serangium maculigerum, was found by an entomologist in Auckland in 2005 and is now spreading throughout the northern areas of New Zealand. This ladybird predates on the Australian Citrus white fly, which is the variety that is established here. The time to monitor for CWF is from August to December, though they can be found most of the year.
4. Flower Moth
Flower moth are usually found towards the end of flowering. A sign flower moth are present is the webbing in the flowers which is created by the caterpillar. The moths lay eggs in the flowers and on the tiny fruit, where the hatching larvae feed on the surface of the fruitlet, causing scarring which we call Rind Spot.
There are a number of varieties of Scale found on Citrus, some are more damaging than others, such as the Californian Red Scale, which can be found in high numbers on the fruit, causing indentation and high reject rates. These scale are tiny, so very hard to detect at the crawler stage. Scale hatch twice a year in New Zealand – August/September and January to March.
6. Greenhouse Thrip
Greenhouse thrip are present between February and April/May, feeding on the surface of touching fruit, causing scarring on the fruit.
Questions for Flowers
Export flowers are required to be insect free for export. This is achieved by spraying regularly and fumigating the flowers before they leave the property.
Many growers do not monitor because of the requirement to spray regularly but there is also a concern about spraying when you do not know what to spray for that is where monitoring comes in. Regular monitoring of the crops you are harvesting will help you to identify any insects or diseases present therefore, allowing you to apply a softer and targeted spray. This is better for the ecology and your health.
1. Two-spotted Mites
These mites are a big problem in many flowers, particularly on Hydrangea and Viburnum. Two-spotted Mites mostly occur in the hot and dry months of summer which causes the leaves to become almost lace like if severely infested. In major infestations, flowers will also be marked by these mites. Two-spotted mites can be difficult to control, needing careful use of the correct spray as soon as the mites are seen that is where monitoring comes in, allowing you to detect and get on top of the mites as soon as they are around. Two weekly monitoring is recommended over the flowering period.
Aphids are one of the first insects seen on the flowers in spring which causes some damage to new shoots. Monitoring to find the Aphids needs to occur from August to September.
3. White Fly
White Fly can be seen all year round but mostly over spring and summer. They lay their eggs on the underside of the leaves and could potentially cause some sooty mould.
Looper and Leafroller are the main caterpillars found on flowers. These insects are mostly found on the flowers or leaves. Leucodendrum is a crop that can be targeted by Leafroller at any time of the year.
5. Flower Thrip
Flower Thrip can do some significant damage to the petals on Tynus and Perris therefore, monitoring is recommended over flowering time.