So, about 5 years ago I started losing entire watermelon crops. Before that, they were gorgeous and huge. I assume the Fusarium came with sèeds I bought of heirloom types like my favorite, Ledmon.
Since there are no resistant watermelon types, I gave up on growing them and haven’t tried grafting.
The Fusarium started affecting my heirloom tomatoes also, so I switched to resistant types.
I recently stumbled upon a video on youtube that talked about spraying an aspirin water solution on tomato plants to combat the effects of Fusarium Wilt.
Does it work on tomatoes and if so, can I do the same for watermelon?
Inoculate the seedlings with Trichoderma spores. Aspirin “might” help by triggering the plants defense mechanism, but not going to directly do anything to the pathogen.
Every year I have fusarium problems with my Big Dena (supposedly F resistant) tomatoes grown in ground in ghouse. This variety has a wonderful acid/sweet taste, is very productive, but I’m constantly removing lower curled leaves as the plant grows.
Each year I replace 5 gal of immediate growing soil (where I’m planting the transplant) but I’m sure there’s residual fusarium in the remaining soil.
Growing willow trees and coppicing them to grind up the wood should net a nice bit of salicylic acid too. I haven’t researched concentrations on that, but they are used to make natural root hormone too.
This year I used estamino rootstock. The only supply I use is the small silicone grafting clips. I use a box cutter or razor blade as grafting knife, a normal grafting knife has a blade too thick. Put them in a warm shady spot for a week covered with a baggie then slowly remove the baggie. This year all seem to be takes, last year I didn’t keep them warm enough and had some failures.
Sadly Trichoderma does not work that well for Fusarium. I have tried many times with cucumbers and had the same result every time.
@Exmil there are Fusarium resistant watermelons, Holmes seeds has quite a few, but they don’t list how resistant they are or which races. Someone else had that info though, I’ll keep looking.
Also another problem I have noticed that looks like Fusarium is cucumber beetle larva feeding on roots. They can remove every single root hair from a plant, so if it pulls up very easily and has a lot of holes in the roots, that could be the problem. Also, Fusarium is pretty host specific, you shouldn’t be getting it on tomatoes from the same source as the watermelons.
I now notice that you’re in Italy so disregard my American watermelon suggestion. Especially since we most likely have different strains of Fusarium than you do. I would imagine there’s some breeding over there as well, but I don’t know who breeds watermelons in Europe.
There is a biological product that Lallemand makes called Lalstop G46 over here. Don’t know if they have a different trade name over there but it’s the one that contains Clonostachys rosea strain J1446. I’ve seen one study comparing it, Bacillus, and Trichoderma and it had nearly 100% control, while the other biologicals had minimal effect. It’s a bit expensive though.
I buy the seeds from Johnnys. They are expensive, the estamino were encapsulated though so they lasted several years. Before that I got some that were not encapsulated and they didn’t last so long. I think the clips I just bought on Amazon.
@Exmil I just do a simple wedge graft, no need for anything fancy. The wedge needs to be long or it gets hard for the clip to keep the slimy rootstock together.
I’ve posted this before, but in case any here would like to see the grafting process for tomatoes and how to heal the grafts here are two videos I made a few years back. I use the 2mm silicon clips like Scott.
How to graft tomatoes - easy and reliable technique
Healing grafted tomatoes over 6 days - full process
I now use the little plastic stakes from Johnnys instead of the bamboo skewers since the don’t mold while being humid during healing. I use DRO141 tx rootstocks and found Paramount seeds had the best prices.
