Sweetcorn help! ;-)

niceirishfella

Hi,

Got a shed load of Sweetcorn plants growing in my polytunnel in grow bags and they have gotten so tall, they are keeling over.
Should I prop them with steaks or is it too late now?
Anyone with lots of experience with Sweetcorn?:pac:

Thanks.

The Sweeper

It's a nodal nightmare!!

But seriously - my first reaction would be that the growbag isn't allowing them to establish deep enough roots to keep themselves upright. Depending on the variety, they do grow to the same height as you.

I think the only way I'd try them in a polytunnel is direct into the ground - they're also wind pollinated, so you'll need to ensure there's some breeze to pollinate them, and plant them in blocks of 4 x 4 (or four rows of as many as you want) for better pollination.

Can you loosen them out of the growbag and plant them in the ground?

It's not a hopeless case but you've your work cut out for you. I'd cultivate the soil in the polytunnel and set up temporary 'fences'. Then loosen the corn out of the bags and plant them in the well-cultvated soil, and tie them loosely to the fences to give them a chance. Then water them in (but don't drown them), so they grow the nodal root system they need to stay upright. Remove the fences as they establish.

From http://msucares.com/crops/corn/corn_rootless.html:

Corn

Why is my young corn falling down?

Several fields have recently had young corn plants falling over.

Corn sometimes has problems developing its nodal root system which causes plants to fall over when the plants get one to two feet tall. Normal shoot development often precedes this scenario, although nutrient deficiency symptoms may be observed, due to poor root exploration. This condition is often referred to as rootless corn syndrome. The ability of corn plants to recover from this condition depends upon favorable environmental conditions and why the nodal roots are failing to develop.

Corn has a two part root system consisting of seminal roots and nodal roots. The seminal root system consists of the radicle and lateral seminal roots which develop below the seed. These roots temporarily anchor the seedling and take up water and nutrients during and shortly after emergence. The seminal roots cease growth by the V3 growth stage. The nodal roots begin developing at emergence and provide structural support and the bulk of nutrient and water uptake during the remainder of the plant's life.

When nodal roots do not develop, the only structure anchoring the plant is the mesocotyl (the shoot from the seed to the crown of the plant). Thus, when the plants develop substantial size, they will fall over, since there is no lateral support for the stem.

There are several reasons why nodal roots may not develop, including shallow planting, poor seed-furrow closure and soil erosion. Corn planted less than one inch deep will move the nodal root origination point up to or above the soil surface, subjecting these roots to many factors that can retard growth (hot, dry and/or compacted soil, herbicide injury or carryover, and surface-feeding insects). Corn planted at the recommended seeding depth (one and a half to two inches deep) will develop the nodal roots below the soil surface, avoiding these potential problems. Corn planted in fairly moist soil may also compact the soil around the seed-furrow, especially on heavy clay soils, causing the furrow to open and present the same problems as shallow planting. Heavy rainfall or wind erosion may also move soil away from the crown of emerged corn plants, especially on light textured soils with raised beds, exposing the nodal root system as well.

Some herbicides labeled for use on corn can inhibit nodal root development. Prowl/Pendimax (pendimethalin) applied preemergence may inhibit nodal root development, often causing considerable root swelling, especially at the tips. Clarity (dicamba) or 2,4-D applied early postemergence may also cause nodal roots to be short and/or fused together.

Rootless corn syndrome is often erroneously blamed on chinch bug damage. Chinch bugs are capable of inhibiting nodal roots, but injury is nearly always the result of sustained, large, and easily observed populations of chinch bugs.

Herbicide carryover may also inhibit root development. However, shoot stunting is normally evident accompanying the root stunting. Herbicide carryover problems typically are more pronounced along field borders where overlapping and applicator slowing occurs.

Corn should likely recover if rainfall or irrigation water is received, which should promote nodal root development. However, dryland fields could sustain considerable stand loss, if rainfall doesn't promote root growth soon. Cultivation may also promote root development, if soil can be moved around the base of plants without knocking them down.

niceirishfella

What a comprehensive reply!
Thank you. I've propped them all up but not transplanted them YET! Will have to soon I think.