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Hi all,

Just wondering if anyone can help me identify this pest and help me treat my beans. Every time I grow beans they seem to take off and then once they start flowering the leaves start to wilt and drop off and tumourous growths appear around where the leaves join the stems and sometimes at the base of the plant. I thought it was something I was doing wrong the first two times but this time I decided not to blame myself as I planted them in good soil in a position they love. Managed to get them growing really well but then the same thing happened. I picked off a couple of leaves that were wilting and found tiny bugs/larvae inside. They have a brownish/creamy casing and a very tiny - about 1-2mm long. I'm presuming this is the problem but can't seem to find any info about it or how to treat the beans online.

Any pearls of wisdom??

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I observe the leaves of my new climbing beans are sporadically dotted with bean fly stings so had me thinking of using neem as a systemic.

Extracted from a German university study,

"Finally, bean seedlings grown from seeds pregerminated for 3 d in neem emulsion were also toxic to western flower thrips."

See http://www.ncbi.nlm.nih.gov/pubmed/12852622

Now, thrips are not bean flies. But neem is supposed to act on most types of sap sucking insects.

I just need to find out what pregermination actually means because soaking bean seeds tend to rot them, as I understand?

While neem is organic, personally I would hesitate to use it on a crop like beans as there are mixed messages about just how safe it is.  I do use it but I try to only use it on my fruit trees rather than vegetables that grow so quickly.  I am probably being extra paranoid but after all the reading I have done I am horrified about just what is allowed and still gets the 'organic' label - hence why I don't buy organic anymore!

 

Very true, Donna. I can think of quite a few organic toxins.

I dug around for info on neem before ordering my first bottle of cold-pressed oil. Seems it's known to cause infertility, should be avoided by pregnant women and definitely not to be ingested by children! Neem seeds are poisonous in large doses.

(It's the same with comfrey. Large doses are bad for the liver and is said to be accumulative in poultry fed on the plant)

I'm interested in what else did you find out that's not quite right with neem?

I have used it as a foliage spray for my vegetables. I just make sure I don't spray at least 5 days before harvest and the vegetables are washed. It's hard to get away without spraying in Brisbane. Even spring onions are attacked by a type of black aphid I've never before seen in Canberra!

PS. the comfrey roots you gave me in May are thriving. Just the other day I shared my first cup of comfrey tea with some of my paw paw friends. Thanks!

 

Erm, Joseph ... the Onion family are about the most pest-proof of any plants I've grown. I plant several batches of seedling Spring Onions each year and nothing except a desperate grasshopper gets to chomp them.

 

If you think of any of these sprays as 'first aid' to help an ailing plant back to health and at the same time addressing the cause: soil nutrition, organic matter, watering, season, aspect, pH you get the picture. Sick plants attract pests and diseases, healthy plants growing in vibrantly-healthy soil rarely get attacked or infested with anything detrimental.

 

Just today Elaine and I went to a 'Bunnings Garden Club' meeting for the first time. The talk was by a rep from Yates. No surprises she was plugging all their products for this and that. In sharp relief is the conventional approach of treating the symptoms (pest, diseases) rather than even attempting to talk about soil health etc which wouldn't necessarily mean they'd be out of business just that their business would change. Anyway ... just looking at the symptoms is OK short-term but no solution in the long term.

And so I thought! Mum used to plant spring onions to deter pests. These spring onions are healthy looking but they still attract black aphids and thrips sometimes. The onions don't seem to be affected by the pests but I prefer to spray for aesthetic reasons (mostly to avoid serving onion leaves with black-purple stains or sooty mold on them).

Remember I mentioned that my Asian greens weren't as badly affected by flea beetles and other pests with less spraying after I replaced Yates All-purpose soluble with organic fertilisers? ;)

From my own observations, pests such as leaf miners, flea beetles, spider mites and aphids (these are the vultures of the pest clan) will only typically attack the older parts of a healthy plant. My broccoli were vibrantly green and blemish-free until they started producing heads. They must redirect their energy to the flowers because the once-healthy leaves slowly turned yellow from ground up and became fair game.

Then there are the caterpillars, grasshoppers and slugs/snails. These have no respect for health and will chomp on whatever they like. 

 

 

 

 

 

OK to clarify part of my reasoning: substitute 'sick' for 'stressed' and it might be clearer then why the Broccoli is looking peaky when it is growing the head. The whole reason for a plant's existence is to make seeds for the next generation so most of its energy at that time would go towards that end as you've observed. Not as we might suppose to make food for us (that's why we grow them, not why they grow!). I have noticed that plants which are reaching the end of their lives do become prey to pests and diseases so I would include that situation in with 'stress'.

 

Caterpillars, Grasshoppers, Slugs and Snails are part of the garbage-collection service in the natural world. They clean up plants like ants clean up dead animals so we're not tripping over rotting carcasses.

If only I could direct the garbage collection service to my compost ... :)

Growing beans: update.

After failing to produce no more than a handful of beans from several successive plantings, my latest crop of climbers and bush beans are doing quite well. The bush beans are robust and flowering vigorously and I've harvested about 30-40 beans from the 7 climbers in the past few weeks.

The difference I think can be attributed to the advice given on this thread, which for me comes down to 3 things:

  • Regular applications of a spray made from garlic, neem, organic soap and chilli (in various combinations depending on time and laziness) of the bean plants in the first 10 days
  • Composting the soil prior to sowing
  • Regular applications of seaweed and powerfeed plus potash

While the plants are not immune to bean fly attacks, they are noticeably healthier without the gradual yellowing and wilting as previously noted.

Some of these bean seeds are packed in the UK so I'd guess this breed has no resistance whatsoever against the bean fly.

So don't give up there's hope yet!

The climbers. The damage you seen on the lower leaves is from last month's hail storm. The yield should improve once I get rid of the pesky rodents.

More young climbers. These have been sprayed once every 2-3 days depending on weather. So far no sign of bean fly spots on the leaves.
Bush beans. The net you see is not large enough to cover the beans so they've been exposed. These have been stung early on but appear ok so far ... time will tell. 

Thanks for posting Joseph.  Your beans are looking good.  Healthy soil and a bit of attention wins again!
Sprayed with what, Joseph?

From memory I've tried the following combinations, not by design but rather by availability and effort required (takes effort to finely chop garlic and chilli):

  • garlic + chilli
  • garlic + chilli + soap
  • neem + garlic + soap
  • neem + chilli + soap
  • neem + soap

All seem to repel bean flies, grass and leaf hoppers.

I also use the same type of spray on the melons (for aphids) and some vegies.

PS. Soap seems to help the spray stick to the leaves. I use a very mild organic soap.

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