Jump to content
Thai Visa Forum

Recommended Posts

Watermelon spraying

The field in front of the house have just started growing watermelons,  Just wondering why they have to chemically spray the young plants every day. Thanks

Link to post
Share on other sites

Maybe just cross the road tomorrow and go ask them. The answers you will get here will not hold weight as that of the Farmer directly.

  • Haha 1
Link to post
Share on other sites

They do it because otherwise they won't be sellable. This is the reason why I stopped growing or eating watermelon here long ago. 

Link to post
Share on other sites

The spray is an insecticide  ,against caterpillars ,that boar in the fruit ,and other insects that that will eat the flowing plants .

We have a lot of watermelons grown around here ,see them spraying all the time .

I would say they is an organic  insecticide but finding it, and it would cost more ,have to be used more often ,hence using chemical insecticides. 

Link to post
Share on other sites
  • 1 month later...
1 hour ago, fondue zoo said:

Does the watermelon take up a lot of the insecticide into the fruit as it grows?

 

)

Not necessarily, it depends on what exact chemistry is being used and the mode of action. 

 

A systemic insecticide, like a neonicotinoid (imidacloprid for example) can enter the plant through roots or foliage and will translocate throughout the plant tissues, although not always into the fruit.  

 

A contact or barrier insecticide like a pyrethroid (permethrin or bifenthrin) does not enter the plant conductive tissues and therefore will only be ingested if you eat the outer skin or don't wash it.

 

An organic program botanical (neem/Azadirachtin, or  pyrethrum/pyrethrins, for example)  would not be much of an issue for toxicity or ingestion. Pyrethrins biodegrade in 12 to 24 hours, and a biological control, like Bt for caterpillars is harmless except to the worms that eat it.

 

They may also be spraying a fungicide, as melons get powdery mildew or anthracnose and other foliar fungal infections which limit leaf surface and photosynthesis and plant production of sugars.  

 

I don't know the specifics of what is being used and I haven't grown watermelon on a commercial scale, but daily spraying of any pesticide is highly unusual and totally unnecessary.  An intelligent, conservative program is designed around complete knowledge of the target pest and it's life cycle, as well as the mode of action and the residual effectiveness of the specific chemistry. Panic and excessive spraying is usually the result of misinformation and unreasonable fear of crop loss. 

 

Kickstart is right about organic program compatible materials needing to be sprayed more often and costing more. Neem products and other botanicals require a weekly application for active infestations, or two week intervals for preventive maintenance. Chemical insecticides usually have a longer period of residual effectiveness and are cheaper, and that's why they are often preferred where environmental contamination and persistance, organic certification or preference is not a consideration. 

 

Its a viscious cycle with high NPK chemical fertilizers that jack the growth but are a pest-magnet.  And then pour on the chemistries to try and control the pests that result from lack of natural resistance.

  • Like 1
  • Thanks 1
Link to post
Share on other sites
On 4/10/2021 at 6:31 AM, fondue zoo said:

I'm always curious as to how effective "companion" plants can be in deterring or trapping watermelon pests.

 

It is certainly something worth consideration.  But of course "how effective" will depend on many factors.

 

Companion Planting with Companion Planting Chart (thespruce.com)

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...