Managing pest and diseases, some strategies
30 years ago there where dozens of powders and solutions to kill most pest and diseases.. Malathion, Derris, Pyrethrum, Permethrin, Bromophos, Mercurous Chloride, Bordeaux mixture and many more. Health and safety has with good reason removed most from the shelves.
Using mercury chemicals to treat clubroot never appealed to me as mercury is so toxic to humans. Also a nerve agent in the same class of compounds as was used to poison an ex Russian spy in Salisbury but much less potent, to kill carrot fly with Bromophos seemed crazy, even if effective. Many pesticides were developed from nerve agents after world war 2.
If you turn to homemade pesticides from plants, it does not necessary mean that it is safer. Many drugs used today are derived from plants and can be potent. Many poisons can come from plants as well, cherry stones contain cyanide! One worry about amazon deforestation is the potential loss of discovery of potent new drugs that could be a cure for many diseases.
Homemade insecticide made from boiling tomato leaves may sound safe. However is it? Tomatoes belong to the same family as deadly night shade and all parts except fruits are poisonous, they contain belladonna Alkaloids just like deadly night shade!
This leaves us an option that many of us choose prevention and understanding of the pests life cycle to control pests and diseases. There are however a few sprays etc still available to use for instance some contact sprays containing fatty acids to kill insects, and also slug pellets.
There are also pheromonal traps, these act as an extreme form of birth control and tend to attract the male of the species by giving out the scent of a female only for the male to come to a sticky end on some sticky substance.
Nematodes is another method available to us amateur gardeners. Nematodes naturally occur in the soil and are part of the soil food web. Some types of nematodes are bad as far as the gardener is concerned, others are good. I have used these as a slug control using a product called Nemaslug. Some people brew their own nematodes, I do not know how successful home made brews are. Nemaslug works best on small slugs and is not very affective against the large Spanish slug. It is also expensive, takes a week to work and lasts about 6 weeks. I used it last year and it seemed to work, with no slug damage on my strawberries for 6 weeks. When the six weeks were up I started getting slug damage. The only problem was it was a very dry period and I cannot exclude that as why I was free of slug damage. This year they were not so effective, but I do believe that they did work this year.
Aphids are often a problem, they also transmit viruses that can do more damage to your plants. Rubbing them out with your fingers, or a jet of water to knock them off the plant does work well. Although not an approved method some people use a few drops of washing up liquid in water and spray the plants.
Flea beetle makes lots of small holes in seedling leaves, it does. not usually affect large plants negatively. One method that I have not used is to attach some sticky tape to a stick. Run this just over your plants. The flea beetle hops off the plant and gets stuck on the sticky tape.
Another way to control flea beetle that I heard of recently is to grow a sacrificial crop of radishes. When they are infested with flea beetle to burn the plants with a flame gun. Apparently it was quite effective over a few seasons to reduce their numbers.
Pinching out your growing tip of your broad beans when the plants are fully grown, discourages black fly but is not 100%, aphids like soft sappy growth.
Some gardeners who garden organically believe that nature produces a balance between plant pests and the plants predators. Spraying with a pesticide kills beneficial and non beneficial insects. This means that there are fewer beneficial insects around next time you get a pest attack.
If undisturbed you will get fewer, or not so severe outbreaks in future years. The problem with this is you have to wait for the predator's to follow the pest attack. Ladybirds and their offspring are very effective once present. Also one ladybird eats many aphids so you need a lot of aphids around! If I see ladybirds I use my fingers or water spray to remove a large portion of aphids, but not all so that the ladybirds can still have a feast and move on when done. Not spraying does seem to rebalance nature into our favor however.
Some people believe in sacrificial plants to attract all the pest away from your produce. I could never see the logic as all you are doing is building up the pests numbers rather than reducing their numbers, so the problem is bigger next year.
Celery fly lays its eggs on celery, parsnips and celeriac in May and July usually. The little maggots can be found inside the leaves which initially are bruised looking then scorched in appearance as the maggots eat the leaves from inside the leaves. We have this onsite most years. Use a barrier method and picking off and burn the affected leaves. Also crop rotation as the maggots pupate in the ground and overwinter
Clubroot is a pain with no cure. Its a soil fungus disease that is soil born. Its also called finger and toes, because that is what your brassica (cabbage family) roots look like. The fungus in the soil causes the plant to produce plant growing hormones in the roots (auxins). This causes the roots to swell and become knobbled. The growth then blocks the tubes that transport water from the roots to the leaves. Without the water the plants suffer badly and you may get a poor harvest or no harvest at all. It is spread by planting plants that have been grown in infected soil, dirt on boots and tools that has come from infected soil. It can live on in the soil for about 17 years if no host plant or host weed is present. It does not like alkaline conditions, so liming your soil and or adding lime around the roots can reduce the severity of the disease.
White rot is another serious fungal disease of allium's, i.e. onion family including garlic, it is soil born and will persist for 8 years if no host plant is grown in that soil. It is spread in the same way as clubroot.
Blight a fungal disease of potatoes and tomatoes, it needs wet leaves to spread and is rapidly fatal for the plant. Tomatoes and potatoes will rot. You can grow Tomatoes under cover to largely avoid, also avoid watering on to the leaves of the plant.
It is possible also to grow disease resistant varieties of vegetables. They are resistant, but not immune to the diseases.
For example Some varieties of brassicas are club root resistant, e.g. Crispus a Brussel sprout is clubroot resistant. Some varieties of potatoes are blight resistant, but the blight has mutated and newer variants may bypass this protection (where else have I heard this recently?). Sarpo Mira is a newer blight resistant variety of potatoes
The best way to garden and avoid pests is prevention and knowing the life cycles of your pests. Growing your plants so that they avoid the pests is a good control method, your plants grow better. Over wintered and early sown peas avoid pea moth caterpillars. Over wintered broad beans avoid the worst of black fly.
Netting is another control mechanism to keep birds, butterflies and squirrels from your crop. Make sure its a small hole size and that leaves do not touch the netting. I have seen cabbage white butterflies fly in and out of so called butterfly netting. They are also happy to stick their rear through the netting to lay eggs.
Birds will sit on netting to weigh it down so they can eat your veg or fruit.
Squirrels will also lift netting up to get under it!
Debris netting is very good, strong, does not tangle, lasts a few years and reasonably priced, much easier to put in place than nylon netting, my prefered general use netting.
Horticultural fleece and enviromesh are both forms of netting to protect your crops. The hole size is so small that its a barrier to insects.
Fleece will also give the plants warmth to stimulate plant growth as well a keep insects out, but not usable in hot weather as you will cook your plants. It is is also delicate and does not last so long.
Enviromesh is expensive but can last for 10 years if treated carefully, but does not give your plants the warmth that fleece does, a good option to reduce carrot root fly.
There are other ways to deal with pests and diseases besides what I have mentioned.
Things to sow in July:
Spring Cabbage
Chicory
Chinese cabbage
Kohl rabi
Lettuce
Peas
Dwarf French Beans
Beetroot
Carrots
Radishes
Turnips
If you are not planning to grow anything after your current crop then why not make the ground work for you by growing a green manure? Green manures are crops grown from seed which are not harvested but dug into the soil or chopped and dropped instead. Some that belong to the legume family capture nitrogen from the air. Do not use mustard seed if you have clubroot as it belongs to the cabbage family.
Kevin
30 years ago there where dozens of powders and solutions to kill most pest and diseases.. Malathion, Derris, Pyrethrum, Permethrin, Bromophos, Mercurous Chloride, Bordeaux mixture and many more. Health and safety has with good reason removed most from the shelves.
Using mercury chemicals to treat clubroot never appealed to me as mercury is so toxic to humans. Also a nerve agent in the same class of compounds as was used to poison an ex Russian spy in Salisbury but much less potent, to kill carrot fly with Bromophos seemed crazy, even if effective. Many pesticides were developed from nerve agents after world war 2.
If you turn to homemade pesticides from plants, it does not necessary mean that it is safer. Many drugs used today are derived from plants and can be potent. Many poisons can come from plants as well, cherry stones contain cyanide! One worry about amazon deforestation is the potential loss of discovery of potent new drugs that could be a cure for many diseases.
Homemade insecticide made from boiling tomato leaves may sound safe. However is it? Tomatoes belong to the same family as deadly night shade and all parts except fruits are poisonous, they contain belladonna Alkaloids just like deadly night shade!
This leaves us an option that many of us choose prevention and understanding of the pests life cycle to control pests and diseases. There are however a few sprays etc still available to use for instance some contact sprays containing fatty acids to kill insects, and also slug pellets.
There are also pheromonal traps, these act as an extreme form of birth control and tend to attract the male of the species by giving out the scent of a female only for the male to come to a sticky end on some sticky substance.
Nematodes is another method available to us amateur gardeners. Nematodes naturally occur in the soil and are part of the soil food web. Some types of nematodes are bad as far as the gardener is concerned, others are good. I have used these as a slug control using a product called Nemaslug. Some people brew their own nematodes, I do not know how successful home made brews are. Nemaslug works best on small slugs and is not very affective against the large Spanish slug. It is also expensive, takes a week to work and lasts about 6 weeks. I used it last year and it seemed to work, with no slug damage on my strawberries for 6 weeks. When the six weeks were up I started getting slug damage. The only problem was it was a very dry period and I cannot exclude that as why I was free of slug damage. This year they were not so effective, but I do believe that they did work this year.
Aphids are often a problem, they also transmit viruses that can do more damage to your plants. Rubbing them out with your fingers, or a jet of water to knock them off the plant does work well. Although not an approved method some people use a few drops of washing up liquid in water and spray the plants.
Flea beetle makes lots of small holes in seedling leaves, it does. not usually affect large plants negatively. One method that I have not used is to attach some sticky tape to a stick. Run this just over your plants. The flea beetle hops off the plant and gets stuck on the sticky tape.
Another way to control flea beetle that I heard of recently is to grow a sacrificial crop of radishes. When they are infested with flea beetle to burn the plants with a flame gun. Apparently it was quite effective over a few seasons to reduce their numbers.
Pinching out your growing tip of your broad beans when the plants are fully grown, discourages black fly but is not 100%, aphids like soft sappy growth.
Some gardeners who garden organically believe that nature produces a balance between plant pests and the plants predators. Spraying with a pesticide kills beneficial and non beneficial insects. This means that there are fewer beneficial insects around next time you get a pest attack.
If undisturbed you will get fewer, or not so severe outbreaks in future years. The problem with this is you have to wait for the predator's to follow the pest attack. Ladybirds and their offspring are very effective once present. Also one ladybird eats many aphids so you need a lot of aphids around! If I see ladybirds I use my fingers or water spray to remove a large portion of aphids, but not all so that the ladybirds can still have a feast and move on when done. Not spraying does seem to rebalance nature into our favor however.
Some people believe in sacrificial plants to attract all the pest away from your produce. I could never see the logic as all you are doing is building up the pests numbers rather than reducing their numbers, so the problem is bigger next year.
Celery fly lays its eggs on celery, parsnips and celeriac in May and July usually. The little maggots can be found inside the leaves which initially are bruised looking then scorched in appearance as the maggots eat the leaves from inside the leaves. We have this onsite most years. Use a barrier method and picking off and burn the affected leaves. Also crop rotation as the maggots pupate in the ground and overwinter
Clubroot is a pain with no cure. Its a soil fungus disease that is soil born. Its also called finger and toes, because that is what your brassica (cabbage family) roots look like. The fungus in the soil causes the plant to produce plant growing hormones in the roots (auxins). This causes the roots to swell and become knobbled. The growth then blocks the tubes that transport water from the roots to the leaves. Without the water the plants suffer badly and you may get a poor harvest or no harvest at all. It is spread by planting plants that have been grown in infected soil, dirt on boots and tools that has come from infected soil. It can live on in the soil for about 17 years if no host plant or host weed is present. It does not like alkaline conditions, so liming your soil and or adding lime around the roots can reduce the severity of the disease.
White rot is another serious fungal disease of allium's, i.e. onion family including garlic, it is soil born and will persist for 8 years if no host plant is grown in that soil. It is spread in the same way as clubroot.
Blight a fungal disease of potatoes and tomatoes, it needs wet leaves to spread and is rapidly fatal for the plant. Tomatoes and potatoes will rot. You can grow Tomatoes under cover to largely avoid, also avoid watering on to the leaves of the plant.
It is possible also to grow disease resistant varieties of vegetables. They are resistant, but not immune to the diseases.
For example Some varieties of brassicas are club root resistant, e.g. Crispus a Brussel sprout is clubroot resistant. Some varieties of potatoes are blight resistant, but the blight has mutated and newer variants may bypass this protection (where else have I heard this recently?). Sarpo Mira is a newer blight resistant variety of potatoes
The best way to garden and avoid pests is prevention and knowing the life cycles of your pests. Growing your plants so that they avoid the pests is a good control method, your plants grow better. Over wintered and early sown peas avoid pea moth caterpillars. Over wintered broad beans avoid the worst of black fly.
Netting is another control mechanism to keep birds, butterflies and squirrels from your crop. Make sure its a small hole size and that leaves do not touch the netting. I have seen cabbage white butterflies fly in and out of so called butterfly netting. They are also happy to stick their rear through the netting to lay eggs.
Birds will sit on netting to weigh it down so they can eat your veg or fruit.
Squirrels will also lift netting up to get under it!
Debris netting is very good, strong, does not tangle, lasts a few years and reasonably priced, much easier to put in place than nylon netting, my prefered general use netting.
Horticultural fleece and enviromesh are both forms of netting to protect your crops. The hole size is so small that its a barrier to insects.
Fleece will also give the plants warmth to stimulate plant growth as well a keep insects out, but not usable in hot weather as you will cook your plants. It is is also delicate and does not last so long.
Enviromesh is expensive but can last for 10 years if treated carefully, but does not give your plants the warmth that fleece does, a good option to reduce carrot root fly.
There are other ways to deal with pests and diseases besides what I have mentioned.
Things to sow in July:
Spring Cabbage
Chicory
Chinese cabbage
Kohl rabi
Lettuce
Peas
Dwarf French Beans
Beetroot
Carrots
Radishes
Turnips
If you are not planning to grow anything after your current crop then why not make the ground work for you by growing a green manure? Green manures are crops grown from seed which are not harvested but dug into the soil or chopped and dropped instead. Some that belong to the legume family capture nitrogen from the air. Do not use mustard seed if you have clubroot as it belongs to the cabbage family.
Kevin