What plague doth spot these vine crop leaves? 8.7.20

It’s Friday and we can use something different. From the pen of the clearly very talented Elizabeth Buck, Cornell Vegetable Program via VegEdge.  (It’s so good, I am sending it to all the list servs! Even Christmas trees!)


Don’t know about VegEdge?  It is a newsletter produced by the Cornell Vegetable Program with LOTS of useful information on vegetable production – including high tunnel/greenhouse production.  You can find out how to subscribe at https://cvp.cce.cornell.edu/newsletter.php


An now on to the ‘edutainment’!


What plague doth spot these vine crop leaves?

“Help Help!” shout the vine crops
so sad in the field
So many foliar diseases
diminishing nice yield.

Scouting is smart
but how much can you do
if you look at diseases
not knowing who’s who?

So I’ve written this poem
You can hang in your home
To know which disease
you need to bring to its knees.

Using this tool you can go
and ID your dear crop.
For now you will know
which disease you must stop.

First one spot then two spots
next three spots and four
I’ll bet you’re about
to see a lot more

Alternaria moves outward
from leaves near the crown.
Spots a quarter inch big
will soon grow and get brown.

Lighter centers can cause targets in melon,
where this disease hits most often.
Soon the foliage goes down
and in the sun fruits will soften.

Now in watermelon,
on the other hand,
darkish lesions occur
with targets less grand.

Anthracnose will change
its look with each crop
After a water soaked start
the similarities drop.

When on muskmelons
and cucumbers, too,

Medium brown pea sized lesions
or leaf distortion is in view.

Now switch to watermelon
and there you will find
dark irregular marks
covering leaves all along vine.

Most other cucurbits,
give less away
look for yellow circular spots
and fruit decay.

Fruit is the real target
of anthracnose’s game
Dark or black sunken lesions
no other disease can claim.


Bacterial diseases?
They’re a real bummer.
Seriously, though, these two
Can ruin your summer.

Both will start as little water soaked spots
And turn into shot holes from small little dots
Both these lesions can ooze and dry to a crust
If there’s a halo further investigation is a must.

Angular stays confined by the veins
Bacterial really is more of a pain.
The first is darker, from yellow to brown
the second is lighter, from white to light brown.

Beware of the fruit spots
Xanthomonas causes a lot.
Those little white dots
will get secondary rots.

Copper is the treatment for either one.
And just for an extra measure of fun
Both bacteria are very hard to stop
if wet weather puts them over the top.


Gummy Stem Blight
Foliar symptoms of gummy
are not very yummy.
I’d be willing to bargain
your lesions start on leaf margins.

Moving from water soaked
to tan and dark brown
Pepper-fleck centered lesions
send spores all around.

And on the stems you will see
bleeding cankers, ugly as can be
On water and plain melons it is the worse,
In all crops it is very hard to reverse

If you try to ignore plecto
your field’ll get wrecked-o
This fungus likes summer squash and zucchini
along with pumpkins, but certainly not tahini.

Small sunken tan spindles
first show up on the stem
Leaf veins and the handles
will be next to get them

Plecto doesn’t skip over the fruit
small spindle to round lesions
Will make you shout “shoot!”

Odd shaped and everywhere
scab lesions really don’t care.
They’re on leaves and stalks
even the fruit can show pox.

More water-soaking to start?
Well, well, what a surprise.
At least it’s pale green and not yellow
As scab first grows in size.

Once they are older
the lesions turn brown
with a nice yellow halo
running around.

And then for a change
a diagnostic trait,
lesion centers drop out
leaves shot-holed – just great.


Septoria Septoria
you bring me euphoria.
I see you so much more
when temps hang near 64.

A cool night disease,
I identify you with ease.
Round tiny marks of beige-white
with a thin brown border in sight.

And best of all,
when you occur in the fall,
black specks mark your middle
making this an easily solved riddle.