| Pesticides the natural way - I |
This is a great program of using natures own eco balance for your own needs. It reduces your pesticide use while increasing the overall health of the plant by not adding poisons. Utilize biologicals rather than chemical pesticides is encouraged because we all have to eat and sleep in this world and integrated pest management makes it that much easier. |
| Red Spider Mites |
 Problem
Red spider mite feeds on leaf cells causing yellowish, speckled marks. Depending on the degree of infestation, damage can range from small chlorotic patches, to dying leaves. Webbing can be found in extreme cases which leads to rapid spread of the spider mites to surrounding plants. The resulting damage can seriously reduce crop yields.
The Solution
Phytoselulus persimilis is a very efficient and cost effective way of controlling red spider mite levels in outdoor crops. Phytosefulus mites can be targeted where spider mite hot spots exist, and they will also travel considerable distances to actively seek out their prey. Whilst sprays can offer limited control, they often miss spider mites on the underside of leaves. Furthermore, harvest intervals should be carefully observed when spraying prior to fruiting. Phytoselulus can be introduced at any time after the risk of frost has passed. |
| Western flower thrips (WFT) |
 Problem
Western flower thrips and now to a lesser extent Onion thrips are serious pests on very many plants causing bleached patches on the undersides of leaves, and in severe attacks whole plants will be defoliated. WFT has become resistant to most pesticides since it was found attacking crops in Europe in the early 1980's.
Western flower thrips - Biology of the pest
The life cycle takes between 2-7 weeks and the eggs are laid at a rate of 2-5/day. Adults live for about 6 weeks. Pupation usually occurs in the soil but it can occur on any horizontal surface. The pest over winters in the soil as a pupa and mobile stages can feed on any greenery left in the glasshouse.
Solution
Amblyseius available in a vermiculite formulation with 10,000 or 50,000/litre may be sprinkled onto low growing bedding or pot crops. Specially formulated breeding colonies of the predator are available in sachets for larger pot crops or salad crops. Orius spp is available in units of 250.
Benefits
CRS sachets provide predators before thrips invasions. Amblyselus can penetrate buds where thrips can avoid sprays. Orius supplement control in heavy infestations. |
 Amblyseius Cacumeris
This predator has been developed for use in a wide range of situations, with the unique controlled release sachets being ideally suited for use on long season crops (eg cucumbers, peppers). The colourless mite looks like a very small Phytoselulus and can be seen moving very rapidly over leaves. It eats 1 + young thrips larvae/day.
Orius spp.
There ore two species of Orius available for WFT control. These are produced in bottles containing 250 predators in a buckwheat/vermiculite mixture. Orius laevigatus is preferable in shorter day lengths, whilst Orius majuscules being larger is also used in the summer months. Adults have been known to lay as many as 150 eggs at rates up to 3/day. The build up of population is dependent on temperature and prey levels, the life cycle taking 25 weeks. Being day length sensitive Orius laevigatus are normally introduced from mid-March and Orius majuscules from mid-late April.
Control
Thrips are difficult to control with chemicals and because of their very rapid multiplication rates Amblysefus should be introduced as soon as the first thrips are seen. Control relies on complete cover of the crops with predatory mites, to catch young thrips larvae as they hatch. Orius on longer term crops would be applied at 1-5/ m2 but should not be used until the pest is seen attacking the crop. |
| Glasshouse Whitefly and its control |
 Problem
The glasshouse Whitefly (Trialeurodes vaporariorum) has been a serious pest of plants in glasshouses during the whole of this century. Both adults and larvae excrete copious amounts of sticky honeydew; black moulds grow on this, smothering plants and making them unsightly. Massive populations develop in plant heads, which together with the black mould kills the plants.
Whitefly - Biology of the pest
Whiteflies can survive outdoors on plants even at temperatures below 0C where infestation can occur from weeds round the greenhouses. Once in the greenhouse adult flies lay eggs on young leaves After hatching ( 1-2 weeks) the young disc like larvae crawl over the leaf and settle. getting bigger with each moulting until pupation (1-2 weeks). The whole life cycle takes 3-7 weeks.
Solution
Encarsia is available on hooked cards (60/card) for hanging in the crop. They are provided in units of 25 cards. designed for easy application to plants. Use as an insurance to control Whiteflies as soon as they infect a crop.
Benefits
- Quick and easy to use
- Controls resistant strains of Whiteflies
- Low cost treatment
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Encarsia formosa
These minute wasps (1.5mm long) attack young whitefly larvae (scales) by stinging and laying eggs within them. On pupation the Whitefly pupae turn black. Each wasp lays 60-100 eggs. and the life cycle takes 2-4 weeks to complete. The parasite will not fly below 20C. Introduction rates vary from 0.5-4 parasites/m2/week.
Control
Successful control depends on two important factors:
1. "Insurance" introductions are made weekly
2. A temperature of 20C+ is required for a short while each day to allow the wasp to fly.
Some pesticides are lethal to Encarsia formosa. Contact your technical manager for guidance. |
 Practical use of Encarsia on crops
Cucumbers: Whiteflies overwinter on the smaller weeds so good clean up in the autumn is essential. Introduce Encarsia throughout the crop from 2 weeks after planting at 1-4/ m2/week.
Tomatoes: Parasites must be introduced throughout the season from ane week after receiving plants on the nursery until the heads are stopped. Care must be taken not to remove leaves with unemerged black scales. Use at rate of 0.5 - 1 parasite/ m2/week.
Ornamentals: It is especially important to clean up glasshouses before introducing new crops. This is sometimes difficult where stock plants are overwintered. In all situations introduce Encarsia at 1-3/ m2/week.
Poinsettias: must have Encarsia introduced onto the crop from receiving the plants until 2 weeks before marketing. Use 1 parasite/3 plants.
Sticky yellow traps are valuable in monitoring for adult whiteflies.
Note: Another species of Whitefly, Bemisia tabaci (the cotton whitefly) is potentially a very serious pest of many glasshouse crops. At present it is controlled under plant quarantine regulations. |
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