? Is this blight ?

Lius · Posted: Wed Jun 10, 2009 7:30 pm Post subject: ? Is this blight ?

Hi,

Can anyone tell from the attached photo of potatoe foliage if this is blight?

This appeared on my first earlies suddenly today, the buds only started to open into flowers yesterday.

I sprayed with Dithane this evening but ir rained straight after, should I spray again and how soon?

MrDamon · Posted: Wed Jun 10, 2009 9:20 pm Post subject:

Looks like it I'm afraid

michael brenock · Posted: Thu Jun 11, 2009 11:21 am Post subject:

almost certainly not the scorching around the edges of the leaves are caused by either sun scorch after a shower or very early sun in the mornings before the dew has disappeared. the potatoes will grow out of it.
michael brenock horticultural advisor (retired)

MrDamon · Posted: Thu Jun 11, 2009 12:43 pm Post subject:

Oh I forgot we had our little heat wave last week Smile

Liparis · Posted: Thu Jun 11, 2009 2:11 pm Post subject:

I would agree on scorch.
Myself, I would expect to see yellowing of the foliage when blight strikes, then the other damage on closer inspection. Blighted potato haulms stand out from the rest like a bletia beacon.
Bill.

Lius · Posted: Thu Jun 11, 2009 7:22 pm Post subject: Blight

I was more worried about the brown blotches / spots on the front of the leaves than the scorching on the edges of the leaves.

What do you think about this picture?

icon · Hazel Tree Joined: 29 Aug 2006 Posts: 13 Location: kerry

sorry but id say certain blight

michael brenock · Posted: Sat Jun 13, 2009 10:39 am Post subject:

most certainly not blight. While i cannot see the underside (should have whitish mould visible) of the leaf the top portion is not displaying the typical symptoms of browning of leaf and bounded by veins of leaf. The damage on leaf could have been caused by rubbing of leaf against a surface.
michael brenock horticultural advisor (retired)

Liparis · Posted: Sat Jun 13, 2009 12:15 pm Post subject:

To me, the foliage looks much too green and fresh. If you stand back from the potatoes you can see a definite loss of colour and contrast in the foliage of a blighted haulm. This normally takes place much sooner that the other symptoms.
But, potatoes don't read books on how they should behave with blight, however, I'd give you better odds than evens on it not being.
Bill.

michael brenock · Posted: Sat Jun 13, 2009 7:14 pm Post subject:

Bill i just love your comments, it keeps me going
michael brenock

Sean Ph'lib · Posted: Sat Jun 13, 2009 7:29 pm Post subject:

I'd be a lot more worried about the effects of Dithane than blight, if I were you.

michael brenock · Posted: Sat Jun 13, 2009 10:04 pm Post subject:

Sean you are really good at this and i enjoy the challenge always. The garden is being neglected and the other addiction I have is sudoku, so its a battle between numbers and garden problems.
Michael brenock

Sean Ph'lib · Posted: Sun Jun 14, 2009 8:59 am Post subject:

Sudoku? I'm puzzled....... Laughing

Michael196 · Posted: Mon Jun 15, 2009 2:32 pm Post subject:

I was looking in a vegtable reference book , the vegtable and herb expert by yer man Hessayon on page 84 he has a picture of browning between veins just like the second picture, has it down as magnesium deficiency:

'' first symptom is yellowing of the tissue between the veins of the leaflets. these yellow areas the turn brown and brittle. Growth is stunted''

Treatment: apply a trace element spray

Prevention: feed regularily during growing season, with a fertliizer which contains magnesium as well as nitrogen phosphates and potash''

What I take from all that is poor soil conditions, to start with. Can be remedied for next year.

michael brenock · Posted: Mon Jun 15, 2009 3:01 pm Post subject:

this is not magnesium deficiency. magnesium deficiency shows up first in older leaves and is corrected by adding epsom salts (magnesium sulphate) to the soil, a teaspoonful in a gallon of watercould treat an area of about 40-50 sq yards, can be used at a more dilute rate 1 tsp in 100 gals water but only in cool weather. When applied to the soil water well in so that roots can get at it. the interveinal yellowing always occurs before the browning. Total yellowing of leaves indicates shortage of Nitrogen or dryness.
Michael brenock horticultural advisor(retired)