Sugar Beet Pests

What does Beet Cyst Nematode (BCN) look like?

It has a characteristic lemon-shaped cyst that attaches to sugar beet roots.

How many eggs will each BCN cyst contain and why do their populations build rapidly?

Similar to PCN, each cyst contains more than 200 eggs, with two or three generations being produced each year

What symptoms of BCN mimic drought stress in sugar beet?

Infected plants may show wilting, stunted growth, and limp leaves similar to drought-affected crops.

How severe can yield losses be from BCN?

Infestations can cause up to 60% yield loss in sugar beet.

Which soil types are more prone to severe BCN problems?

Light sandy soils pose a greater risk, and organic or black sands are also higher risk because they retain more moisture.

Which common weeds can host BCN?

• Fat-hen and orache are hosts, both belonging to the same family as sugar beet

• Fodder and weed beet

• OSR and shepherds purse

What are key IPM steps for managing BCN?

• Widen rotations between sugar beet and brassica family crops

• Control host weeds (shepherds purse, fat hen and orache), OSR and weed beet volunteers

• Test soil for BCN prior to drilling

• Grow tolerant varieties (Daphna)

What levels of BCN would warrant a tolerant sugar beet variety such as Daphna to be grown?

If > 10 eggs/g of dry soil

What pests make up the soil pest complex in sugar beet?

Millipedes, symphalids (which develop more legs as they grow), and springtails are the three main pests

How do millipedes, cymphalids, or springtails damage sugar beet?

They feed on roots and stems, often causing blackened roots. They may still be attached when symptoms are discovered - severity of damage depends on soil moisture levels

Which seed treatment can help reduce soil pest complex damage in sugar beet?

Force ST (tefluthrin) provides partial protection for a few weeks through a vapor effect.

What must sugar beet seed be attached to before Force ST (tefluthrin) seed treatment can be applied?

A clay carrier particle

What does the pygmy beetle do to sugar beet plants?

It feeds underground on the stem base and can also chew holes in developing leaves above ground.

How can damage by pygmy beetle be reduced?

• Using Force ST (tefluthrin) seed treatment can lessen the underground feeding impact.

• Pyrethroids used against beet flea beetle such as Hallmark (llambda-cyhalothrin) give incidental control of above ground activity

What damage do field thrips cause in sugar beet?

They feed on the leaf surface of young sugar beet plants (can achieve incidental control from pyrethroids used against other pests)

Why is wireworm generally uncommon in sugar beet?

Grass is rarely grown in the same rotation as sugar beet, limiting wireworm populations.

How can damage be mitigated in sugar beet if wireworms are suspected?

Force ST (tefluthrin) seed treatment helps limit wireworm feeding on sugar beet roots.

What problem do field mice create in sugar beet fields?

They dig up the seed to eat and leave the clay carrier pellet behind - more of a problem on headlands alongside woodland

Why is seed consumption by mice more likely in dry seasons?

Mice won’t eat the seed once it has chitted, so if soil moisture is low, germination is delayed, giving mice more time to feed - substantial yield loss can occur if so

How can drilling practices minimise mouse damage to sugar beet?

Drilling deeper and rolling the soil make it harder for mice to locate the seeds.

Which additional measures other than drilling deeper and rolling help manage mice in sugar beet fields?

Cleaning up any seed spillages and encouraging barn owl nesting to control mouse populations naturally. Rodenticides or traps are discouraged.

How does beet leaf miner damage sugar beet foliage?

White eggs are laid on the underside of the leaf which hatch after 4 to 5 days. The larvae then feed within the leaf tissue creating blister-like mines over a two-week period, dropping to the soil to pupate.

How many generations does beet leaf miner typically have each season?

There are usually three, occurring in April, June, and August.

Why don’t rotation changes affect beet leaf miner incidence?

Adults can travel long distances, making local crop rotations ineffective for reducing their population.

What is the spray threshold for beet leaf miner in sugar beet?

Add the number of eggs and living larvae per plant; if it exceeds the square of the current true leaf count per plant, insecticide treatment may be warranted.

Which insecticide has a specific label claim for beet leaf miner?

Hallmark Zeon (lambda-cyhalothrin) is labeled, though other insecticides used for different pests often provide incidental control.

Why is it difficult to control beet leaf miner with pyrethroids?

They are not systemic and as the eggs are laid on the underside of the leaf it is difficult to achieve effective coverage - egg hatch is the most effective spray timing

When do free-living nematodes (FLN) commonly affect sugar beet?

When grown on light sandy organic soils with wet early-spring conditions in the first few weeks after germination - potentially causing up to 30% yield loss.

Why does FLN damage only occur on light sandy organic soils in sugar beet?

The FLN cannot move freely in well structured soils

How do FLN feed on sugar beet seedlings?

They stab the roots with their needle-like mouthparts

What are the symptoms of FLN damage in sugar beet?

Stunted growth and fangled roots (forked/pointy)

What can be done to find out FLN levels in the soil?

Soil tests can be performed, however field history should give a good indicaition

How can FLN be managed in sugar beet?

NEMguard DE (garlic) can be applied in the row at drilling at 10 kg/ha for good reduction - BBRO recommendation on land with a history of FLN damage

What does beet flea beetle feeding look like on sugar beet leaves?

They eat small pits in cotyledons leaves and petioles (similar to cabbage stem flea beetle damage in oilseed rape) - as the leaves get bigger so will the holes.

When will beet flea beetle invade a sugar beet crop?

In the spring

When would damage from beet flea beetle be the most severe?

In dry sunny weather when crop growth is slow

Does beet flea beetle larvae feeding on roots after eggs are laid on the soil significantly affect sugar beet yield?

No, sugar beet usually outgrows any root feeding, making yield losses uncommon.

Which insecticides can control beet flea beetles if the damage is holding back young sugar beet seedlings?

Hallmark Zeon (lambda-cyhalothrin) and Decis Protech (deltamethrin) are approved pyrethroids for this purpose.

Why are peach potato aphids considered the main pest in sugar beet?

They transmit virus yellows such as Beet Yellowing Virus (BYV), Beet Mild Yellowing Virus (BMYV) and Beet Chlorosis Virus (BChV) which can reduce yield by up to 50% and lower sugar content.

How severe can the damage from yellows viruses vectored by peach potato aphids be in sugar beet?

It can cause a major reduction in beet yield (up to 50%) and sugar content

What are the visible symptoms of the viruses vectored by peach potato aphid in sugar beet?

Yellow circular patches across the field

What do peach potato aphids do once they have flown into a sugar beet crop?

They give birth to non-winged aphids which can cause yellows virus across the whole field as they spread

How do severe frosts in January or February and cold winters affect peach potato aphid populations in sugar beet?

Frosts kill overwintering aphids, while cold winters lower pressures and delay their arrival, reducing early-season virus transmission.

When will damage from peach potato aphids be at its worst in sugar beet?

In mild winters as there are less frosts to kill overwintering aphids - leads to early season infection especially in a warm spring

Which peach potato aphids will not carry virus yellows viruses?

Those that fly in from peach trees that have not fed on infected material

At what point does sugar beet become less susceptible to virus yellows?

When matured (12 true leaf stage) - getting the beet growing quickly to ensure good establishment is essential

Which agronomic practices help sugar beet quickly reach 12 true leaves and establish well to avoid damage from peach potato aphid pressure and virus yellows infection impacting yield?

• Ensure rapid and even crop emergence:

  • Using primed seed before being pelleted to ensure quick germination

  • Preparing a fine firm seedbed with optimum pH (critical 6.0)

  • Providing adequate nutrition pre and post drilling

• Growing a nurse crop to reduce wind erosion and to disguise the sugar beet from aphids

• Encouraging aphid predators (ladybirds, hover flies etc) by growing margin strips of flowering species

• Maintain good hygiene of beet piles

• Destruction of nearby cover crops which may host aphids at least 6 weeks prior to drilling sugar beet

What three things can be done to ensure rapid and even crop emergence in sugar beet to avoid damage from peach potato aphid pressure and virus yellows infection impacting yield?

• Using primed seed before being pelleted to ensure quick germination

• Preparing a fine firm seedbed with optimum pH (critical 6.0)

• Providing adequate nutrition pre and post drilling

How can a barley nurse crop in sugar beet help with establishment and to avoid damage from peach potato aphid pressure and virus yellows infection impacting yield?

It reduces wind erosion and disguises the sugar beet from aphids

How can destroying nearby cover crops 6 weeks prior to drilling help reduce peach potato aphid pressure?

Nearby covers may host aphids and so removing them prevents the aphids being in close proximity to where the sugar beet is grown

How would a barley nurse crop in sugar beet be managed?

A low rate graminicide is used once the sugar beet has established to desicate the barley so it doesn’t compete

What are some partial virus yellows tolerant sugar beet varieties?

Merushka, Generosa, and ST Tweed exhibit partial tolerance to virus yellows.

What are the recommended aphid spray thresholds in sugar beet?

• Up to 12 true leaves: 1 non-winged green aphid per 4 plants.

• 12 to 16 leaves: 1 non-winged green aphid per plant.

Which insecticides are labeled for aphid control in sugar beet?

• Insyst (acetamiprid) - from 2 true leaf stage (1 per crop)

• Teppeki (flonicamid) - from 6 to 8 true leaves (1 per crop)

Why should pyrethroids be avoided for peach potato aphids in sugar beet?

80% of peach potato aphid populations are resistant to pyrethroids, making them ineffective and risking further resistance buildup

When and where do black bean aphids colonise a sugar beet crop?

They colonise on the underside of the leaves in the centre of the plant late in the season

Why is black bean aphid not a major concern for yield in sugar beet?

It does not transmit viruses, and direct feeding damage alone rarely justifies an insecticide application as it doesn’t impact yield.

Which product can be used to control black bean aphid if it becomes economically relevant?

Teppeki (flonicamid) has a label claim

What damage do silver y moth caterpillars cause in sugar beet?

They eat holes in the leaves, reducing photosynthetic area (bright green caterpillar)

What can be helpful in washing silver y moth caterpillars down to the soil where they cannot feed in sugar beet?

Heavy rain or irrigation

What is the threshold for treating silver y moth caterpillars in sugar beet?

5 caterpillars of any species per plant

Which pyrethroid product has label claims for silver y moth control in sugar beet?

Cythrin 500 EC (cypermethrin) - use high water volume (600L+) and only spray when necessary as beneficials will be affected

How can cutworms affect sugar beet and which sprays might be used if needed?

They generally do not harm yield or quality, but Cythrin 500 EC (cypermethrin) or Hallmark Zeon (llamba-cyhalothrin) may be applied at egg hatch if large numbers are seen before they drop to the soil

What damage do birds cause in sugar beet?

Birds can eat and tear off the cotyledons, but sugar beet typically grows away from any damage as the true leaves emerge

Where do rabbits typically feed on sugar beet and how can they be deterred?

They enter from the headlands/woodlands, grazing the outside edge of the field; fencing is commonly used for control.

How do hares typically differ from rabbits in sugar beet feeding?

Hares often feed in the middle of fields, creating patches of grazing damage away from the edges.

Which conditions prompted an outbreak of beet moth in sugar beet in 2022 in Cambridgeshire and Suffolk?

Excessive hot and dry weather allowed beet moth caterpillars to thrive, feeding on stems, heart leaves and upper roots.

What non-chemical methods are available for beet moth control?

Ploughing down any beet remnants or specific areas where an infestation was seen

Which product can be used to control beet moth in sugar beet?

Cythrin 500 EC (cypermethrin) is one of the labeled insecticides for beet moth infestations - high water volume needed

What damage do beet moth caterpillars cause in sugar beet?

The feed on the base of the stem, on the heart leaves and at the top of the roots

What do stem nematodes do to sugar beet?

The occasional pest distorts growth, lowering yield and sugar content

How can stem nematodes be managed in sugar beet?

• Widen the rotation between host crops such as oats, rye, maize, peas and beans

• Control host weeds such as chickweed, cleavers, runch, groundsel, wild oats and bent grasses within the rotation

• Avoid introducing stem nematode in infested field bean seed (ensure seed is tested)

What are some examples of host crops of stem nematode which can impact sugar beet if grown within the rotation?

Oats, rye, maize, peas and beans

What are some examples of host weeds of stem nematode which can impact sugar beet if not controlled?

Chickweed, cleavers, runch, groundsel, wild oats and bent grasses