Well, lettuce root aphid has certainly made itself known here, out of 30 metres of lettuce , 8-9 metres has disappeared, and a good percentage of the rest has been slowed and weakened.
Now interestingly there was a very definite pattern to the destruction. The first lettuces to be affected in my north-south orientated beds were mostly at the north-east corner, and were always Chartwell. (each bed had a very similar planting pattern) Then the aphid spread in a south westerly direction taking out, Redlo, Diablotin, Mottistone, Nymans, Intred, Freckles and Maravilla. Now the interesting part – the damage seemed to stop at a line of Bijou and Navarra, and didn’t continue (too much) past that line onto lettuces behind.
Either this means, that along with Bijou and Navarra the lettuce behind are more resistant to aphid (Red fire, Senorita, Cerbiatta, Mazur, Benmore, Lollo Biondi) or the Bijou and Navarra actively stopped the spread. Actually Cerbiatta and LB succumbed most out all those.
Navarra is definitely the lettuce that has been affected least, in that its growth is normal, not subdued. Next year I shall certainly grow more of this one and mix it up in the beds for summer lettuce . In fact looking online it says Navarra is root aphid resistant and I can confirm that! I wonder what others have similar resistance.
Another interesting observation : is the most damaged beds were from mid june plantings from a mid may sowing, and were first picked from the 7th July and then weekly. Now the beds with least damage, in fact hardly any really, perhaps a normal expected amount, were from the same sowing, but were planted out a week or so later and were left unpicked or at least picked much less than the first batch. It seems the root aphid certainly homed in on and caused more damage to the lettuces that were picked regularly and so were smaller / less able to resist.
As for alternatives to next year, yes Frenzy has been a total star here, first time growing it and I wish I had sowed more, it’s a really high yielding, pest resistant and beautiful plant! Late may sowing here is saving the day currently, also a late may/early june sowing of indigo radicchio is now almost ready for harvest and will prove useful over the next two weeks. Also a late june sowing of bubikopf is almost ready for first leaves, again very welcome! But I forgot the late june sowing of Frenzy! Ah how I am kicking myself for that! I would even consider chard next year, even though I don’t actually like it very much! Perhaps an early july sowing of oriental leaves as a reserve might be an idea? Under a fleece hooped cloche to keep out insects but not get as hot as if resting on top, might be worth a try.
But as Charles says this was probably a bad year for them, as such a mild winter and next year will be something else! But hope this info is useful anyway
Dan