Not sure if nutrient problem or disease - leaves

[mcsprint71]

Hi all, posting from Melbourne, Australia, wherein we have just had a 40 degree day (celcius). I have wondered for several years why my leaves tend to yellow with necrotic areas (generally starting with the older leaves and working upwards). I haven't noticed any wilting. I've researched this one to the nth degree (well, I guess nth might include sending samples to the lab - so maybe nth-1 degee. The plants seem to lose most of their leaves by the end. Looking at the photos, do you think it is a disease, or perhaps potassium deficienc whereby nutrients are translocating to the fruit? There are several varieties with Tommy Toe appearing the most affected. I'm not concerned about the yellowing of the older leaves - it's the necrotic areas I'm wondering about. Only one variety has had fruit picked (Kotlas). Soil has had dolomite lime, compost, blood and bone and two light applications of potassium sulphate (last one recently). They also get foliar feeds of seaweed, sometimes a small dose of fish emulsion, some molasses and some compost tea depending on the immediate effect as measured by increase in brix. Brix of leaf samples have been OK (10-13 depending on variety). Any thoughts? Same thing happened last year - yield was about 40kgs from an area of about 10m2 so they did quite well although the later maturing varieties did not do as well. The irrigated by a drip system getting around 40mm every 5 days (calculated using crop factors, evapotranspiration etc).

[Polar_Lace]

If you'd only read the posts above yours; you'd be able to solve the problem. Check out this link here: Tomato Problem Solver and other helpful links

It's under Tomato Problem Solver.

[amideutch]

mcsprint, I read somewhere as the plant matures and fruit is being produced more and more nutrients are bypassing the bottom leaves so as to support new growth and the maturing fruit. So another words this is normal and I see it on my plants as well. Ami

[mcsprint71]

Hi Polar Lace, Yes, i had read the post and have gone through the links you mentioned again (have seen most of them before) but none of the photos or descriptions seemed to match mine. Thanks again though.

[mcsprint71]

Thanks Amideutch - if that is the case I would be most thankful. If not, if anyone else has anything to add, I am open to suggestions. I've noticed that with one indeterminate variety, Tommy Toe, it's yellowing is quite pervasive even prior to fruit ripening.

[Polar_Lace]

So, mcsprint; none of these pics look like what's happening to your plant leaves: Disorders of Tomato Leaves ?

[mcsprint71]

There may be one or two that look slightly similar, but when matched with the symptoms, no. I'm asking for other's opinions - I've been over the websites numerous times. Do have an opinion or are you just referring to the websites?

[mcsprint71]

Anyone for Powdery mildew?

[troad]

mcsprint71

http://www.ipmimages.org/browse/deta...imgnum=5368846

from a link provided by Polar Lace as IPM images Tomato

Now I need to look this up too. Looks familiar.

Powdery mildew pretty obvious and not showing in your pictures that I can see. Also how much is 40 mm of water every 5 days? Do you let plants show any wilt before watering?

Len

[Polar_Lace]

Not Powdery mildew!



tomato leaf mold !!!

Click on this Link just above (in the words "tomato leaf mold") study what the page says. And the letters came out huge when I did a copy & paste. When you get to that page, then click on the picture links in front of the description. ie: Image - 1436105, 5368846, etc.

[troad]

DID NOT SAY IT WAS POWDERY MILDEW .

Figured mcsprint could read the Tomato leaf mold label. Note I said I could not see mildew in his pictures.

Remind me not to get on your wrong side. (Smile)

[Polar_Lace]

Originally Posted by mcsprint71

Anyone for Powdery mildew?

Not me, mcsprint71 said it.

[troad]

Post # 8 was mcsprints reference to powdery mildew
Post # 9 was my refering him to look at the Tomato leaf mold as a possibility instead of powdery mildew.

I only included the reference to you as a way of noting that you were providing a possible solution other than just giving a broad spectrum of places to look. I will bow out now.

[Polar_Lace]

mcsprint71 - (generally starting with the older leaves and working upwards)

I looked further into those words and came up with this: excerpted from this page: Tomato Diseases

SEPTORIA LEAF SPOT

This destructive disease of tomato foliage (fruit is rarely infected) is caused by the fungus Septoria lycopersici. Infection usually occurs on the lower leaves near the ground, after plants begin to set fruit. Numerous small, water-soaked spots with dark borders surrounding a light gray center appear on the older leaves. Black specks, which are spore-producing bodies, can be seen in the center of the spots. Severely spotted leaves turn yellow, die and fall off the plant. The fungus is most active when temperatures range from 60 to 80° F and humidity is high. Defoliation weakens the plant, reduces the size and quality of the fruit, and exposes the fruit to sunscald (see below). The fungus can overwinter on crop residue from previous crops, decaying vegetation and some wild hosts related to tomato.

Prevention and Treatment: Currently grown tomato cultivars are susceptible to Septoria leaf spot. Crop rotation and sanitation will reduce the amount of inoculum. Repeated fungicide applications (see late blight) will keep the disease in check.

Here's where you can see the leaves in progression: (different stages) Septoria Leaf Spot Images

[mcsprint71]

Thanks Polarlace and Troad. I posed Powdery Mildew as a possibility only as the image http://aggie-horticulture.tamu.edu/t...leaves/21.html looked the most like some of mine - despite not being able to see any powdery substance under a magnifying glass. this classifying is tricky - whilst I agree that leaf mould does look similar, mostly it doesn't.
40mm is around 1&3/5inches. I've been basing it on a crop factor of 1.15 but perhaps I shouild reduce it. Use drip system. No, I don't usually wait for sign of wilt before watering.Do you think I am applying too much water Troad?