Tomato Yellow leaf Curl VIrus

[imafan26]

TYLCV and tomato spotted wilt are the two most pressing viruses of tomatoes where I live. Since I first got TYLCV from momotaro in 2011, it has never gone away. At first they said it was not seed borne, but now it probably is and in 2011, I did not have it until I planted momotaro, so I suspected then it was seed borne.

TYLCV is transmitted by sweet potato whiteflies and it is a chronic problem in the tropics where there is no winter to kill off the diseased hosts or the pests. Tomato is the preferred host that expresses the worst symptoms. causing stunting of new growth after the plants are infected with chlorotic upward curling leaves. Fruit on infected plants that formed before infection are still good, but seeds should not be saved. It only takes 10 minutes of feeding from a virus carrying white fly to infect a tomato.

It was difficult to find TYLCV resistant tomatoes in the early years, only a handful of cultivars were available. There still are not that many TYLCV resistant tomatoes. However, I have found mostly by accident that there are some tomatoes that are not listed as resistant, but have natural resistance, like sweet pea currant. The bonus is that sweet pea is actually a tomato I like and has very good disease resitance.

I can't say that for most of the TYLCV resistant tomatoes. They do have fairly good disease resistance except to mildew which is a big one in a hot humid climate. Almost all of the TYCLCV tomatoes with known resistance are determinate. Not my favorite kind of tomato because I prefer not to get a lot of tomatoes all at once. The tomatoes were pretty bad, dwarf champion II, to o.k. if they are cooked. I don't have very high standards for tomatoes. I don't like acidic, seedy, mushy, or tomatoes with "plastic" skins. Some of the newer tomatoes have better flavor, but they won't win any taste tests. It is better than no tomatoes at all. Most of the temperate varieties are not very heat resistant and will stop producing for me once the temperatures go over 85 degrees. This year, it has been a little cooler. I am only averaging 82 degrees in July, which is already weird. However August-October are the hottest months.

I am able to grow some tomatoes that do not have known resistance in tree bags as long as I can keep a good seal on the bags. It also helps that this is not a bad white fly year.

Recently, I am finding break through virus symptoms on tomatoes that are otherwise resistant. One on a sweet pea currant, and another on Sun King. It does not happen on all plants just on a single individual. I can only control them by culling the infected plants as soon as I recognize the virus symptoms, to avoid building a better bug.

There has been some advances in research on this virus since I first encountered it. I tried not growing tomatoes for two years to try to stop the virus. However, it did not matter, the tomatoes still got virus. Now, with the tree bags, I can protect the shorter tomatoes up to five feet. The bags will not stop disease or mites. I have to make sure the bags are sealed on the bottom and there are no holes in the bags, which can happen when the bags snag on the trellis. This means that I cannot grow most indeterminates. There are only a few indeterminates listed with TYLCV resistance, but there are also a few unlisted varieties with natural resistance.

I recently found out with the break through virus plants, that resistance is not immunity. It can still be an asymptomatic host. Most of the time TYLCV symptoms only occur on tomatoes. I knew there had to be asymptomatic hosts because the moratorium did not work so the white flies were still able to transmit virus. I was looking to find out what I could plant that would not be a host.

Well to my surprise, most of the plants I am growing are alternate asymptomatic hosts. Some beans may even express the disease. None of my beans have expressed the virus. Cabbages, cucurbits, other solanaceous crops (eggplant, peppers), hibiscus, okra, night shades and weeds are alternate asymptomatic hosts as well. There isn't enough research to determine how well the virus is taken up by white flies from the asymptomatic hosts. It would be hard to do, because, they are asymptomatic hosts, so which ones are better at transmitting the virus and which are not? In my yard, there are so many choices.

This is not going to go away, like basil downy mildew, I just have to grow plants that can live with it or plants I can protect.

https://ipm.ucanr.edu/legacy_assets/pdf ... rifold.pdf