Tomato Update

I still haven’t lost any more tomato plants.  I have been spraying them after each rain and I guess that has been working.  It hasn’t rained for a whole week up until today, and there is some nice lush green new growth on top – not marred by the phototoxic “burn” of the phosphorous acid.

I have never applied regular chemical sprays in my vegetable garden in all my 40+ years of gardening.  My crops are normally 99+% organically grown, not because I have any fanatical fear of modern crop protection chemicals or synthetic nitrogen but because I just don’t normally need them.  The soil is fertile because I till in cover crops and lots of composted wood chips.  And this year I made my own fish emulsion fertilizer out of all the filleted carcasses of the bluefish I caught this spring.  If I were to use pesticides the decision to do so would be based on the same IPM/plant health care principles I use when caring for a client’s trees.  First watch plants for potentially damaging pests, then intervene only when those pests reach a threshold population.  For me the threshold is losing the crop – I’m not trying to please any fussy supermarket shoppers that would freak if they found a caterpillar on their broccoli.  When I do nothing, natural predators usually keep the pests under control.

Pardon the digression, back to the tomatoes.  I actually feel kind of lucky that I detected the late blight in time.  Apparently the disease is still rampant in our area.  Just last Saturday I was at a client’s property and she showed me her sick tomato plants.  I advised her to take a sample to the Montgomery County Cooperative Extension office in Creamery.  When I came back to do the tree work on Friday the plants were gone.  She lost them all!  And these were established plants from a reputable source pretty far from the nearest neighbor.

And in Harleysville there is a huge community garden I can’t help gawking at every time I drive by.  Beautiful vegetable plants of all kinds immaculately maintained.  But driving by on Friday it appeared they were about to lose the tomatoes – hundreds of plants that appeared perfect up until now.

So this story is not over.


Update on Tomato Late Blight

It looks like I might not lose my remaining tomato plants.  Last Saturday – 1 week ago today – I removed and burned all of the plants that showed severe symptoms.  But most of the plants had some part that looked infected, and instead of destroying them I pruned out the bad parts.  I have been spraying with Daconil, and a week ago I started also using Agrifos – a fungicide containing potassium salts of phosphorous acid.  This is a material that can possibly be used by organic gardeners.  I have used Agrifos experimentally, along with a material to enable it to penetrate the bark, on trees, and just learned it’s registered for food crops also.  In the past week I have seen no spread of the late blight disease in  my garden.

Oh, and by the way, I got my first ripe tomatoes this week.  The earliest in the summer I can ever remember.  They are on the Rutgers’ Mortons that are advertised to be an early ripener.  I guess they are!

More on Tomato Late Blight

What Should the Home Gardener Do?

So up to now the only advice I have heard has been, basically, :  if you have late blight there is nothing you can do to save your plants – rip them all out and carefully dispose of them to prevent the spread of the pathogen.  But today, I found some more in-depth advice on the Penn State Master Gardeners blog.  Check these 2 very interesting articles:

* Late Blight – What Should the Home Gardener Do? – Rescuing Plants

* Late Blight – What Should the Home Gardener Do? – Destroying Plants

You need to click Permalink at the bottom of the articles to see the comments.

Also, here are 2 good articles that explain a little about who and what are responsible for this problem.

* Greenhouse Grower – Disease Costs Bonnie Plants $1 M in Recall

* Garden Detective – Alert – Late Blight Disease… and Update – Late Blight Disease


!! UPDATE !!


Recently I sent samples of my unhealthy tomato plants to the Plant Disease Clinic at Penn State.  They called me right back and confirmed that my plants had late blight.  If you grow tomatoes PLEASE READ my previous articleabout late blight, and please examine your plants.  This is an extremely serious situation.  And if you do have it, it affects not only you but your neighbors and any local tomato farmers!



A couple of weeks ago I bought a tomato plant at Home Depot and planted it in a barrel on my deck.  Shortly after planting it, it developed severe disease symptoms, so I pulled it out and tossed it in the weeds.

Then last Monday (6/29) I got an email message from Rutgers University Ag. Station, warning that the Northeastern U.S. has a disease problem that is different from other years.

The disease is late blight (Phytopthora infestans).  This is the disease that caused the Irish potato famine.  It kills infected tomato, potato and other related species of plants VERY QUICKLY and is also EXTREMELY CONTAGIOUS.  The cool wet weather we’ve experienced is the ideal condition for late blight development.

But what’s really different about this year is that late blight has never been seen this early in the season over a large region.  And worst of all, infected plants have been distributed from Ohio to Maine through large retail stores that sell a big volume of plants all originating from the same supplier (Bonnie Plants, of Georgia, according to sources I located on the internet).

So yesterday, I stopped at the same Home Depot and tried to warn the person in charge of the plant department.  She said “what do you want from me?”  I was only trying to be helpful, but that wasn’t at all appreciated.  I guess there’s a lot of money at stake for these big companies, but I do not agree with their apparent unwillingness to face up to the problem.  Then I went home and examined the tomato plants in my garden, about 80 plants, mostly heirlooms I grew from seed.  Five of the Rutgers Ramapos were infected with late blight and I yanked them (and disposed of the properly this time!)

So the message is monitor your tomato plants VIGILANTLY to watch for late blight symptoms, especially is you got some of them at what the Rutgers and Penn State alerts refer to as “the Big Box Stores.”  The wet leaf lesions and dark colored lesions on the stems are quite obvious to the naked eye.

infected leaf and stem on Ramapo tomato in my garden

infected leaf and stem on Ramapo tomato in my garden

If you find infected plants, remove them immediately, don’t compost them-bag them and get rid of them to reduce the chance of spreading the innoculum.  For more info go to