Hailstorms and crop impact

The hail storm over the weekend caused scattered damage in the Annapolis Valley, as well as in Hants, Colchester, and Cumberland Counties.  The degree of damage depends a lot on location and crop type, as well as on wind velocity, the size and shape of the hailstones, and how long the hail lasted.  The warm, wet weather that followed the storm can exacerbate disease problems, especially bacterial infections.

Fig. 1. Healing hail damage on butternut squash,
two weeks post-storm.

Crops with large leaves such as Cucurbits will typically look pretty destroyed, but, depending on the severity of the damage to the leaves, and how well the fruit were protected, might pull out of it with minimal yield loss.  If the Cucurbits are on a drip system, a little extra nitrogen will encourage the regeneration of leafy growth.  Damaged zucchinis and summer squash should be removed.  Leaving damaged fruits on the plant, which are unlikely to be marketable, will be a drain on the plant's resources and could result in more prolonged yield losses.  Depending on the severity of damage, many winter squash will scar-over (Figure 1, Figure 2).  Healed scars should not pose a disease risk, but may render the fruit undesirable to some buyers.

Fig 2. Healed hail damage on butternut squash,
seven weeks post-storm.

Other crops that are susceptible to bacterial rots (Figure 3) such as onions will have long-lasting damage - crop injury (Figure 4) opens the door for bacterial infection, which quickly spreads down the leaves into the bulbs.  Dead tissue is prime for stemphylium infection.  Growers are encouraged to continue with preventative stemphylium sprays.  Copper may help with bacterial infection, but results have been poor on onions in the past.

Leaf loss in crops close to harvest such as sweet corn or root crops should have minimal effects on yield.  However, direct impact on sweet corn ears can render them unmarketable, depending on the degree of damage.

Fruiting vegetables such as peppers will be more prone to sunburn if protective foliage has been badly damaged.  Fruits that have taken a direct hit, depending on the size of the hail stone and the velocity of the strike, can be unmarketable.

Fig. 3. Bacterial infection spreading down an
onion leaf

Losses of flowers and small fruit will reduce yield and delay harvest in crops such as green beans.

Wounds in plant tissue open the door for diseases to come in.  It is recommended that a protectant such as copper or Bravo be applied (if labeled) for your damaged crop, which will help guard against infection while the plant heals.  Always read and follow the label, the most up to date labels can be found on the Health Canada website.

If you have Crop Insurance, it is recommended that you reach out so that they can document the damage.  Should a claim be necessary down the road, they will have a record of how extensive the damage was, which will make filing a claim easier.  The days just after a hail storm are often the worse.  Apply a protectant, maybe give your crop a bit of extra fertility, if appropriate, and then come back in a week to see how things look.  If the crop pulls out of the damage, then no insurance claim needs to be filed.  Registered farms in Nova Scotia shouldn't hesitate to contact Perennia if you are unsure of best management practices in crops that have been affected by adverse weather.

Fig 4. Hail damage on onions

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Garlic scape removal

If you haven’t signed up for it before, OMAFRA has a fantastic vegetable blog.  A couple of years ago, Travis Cranmer, OMAFRA’s Allium Specialist, wrote a great piece about the benefits of removing garlic scapes.

Figure 1. Yield and bulb weight in response to scape removal timing of
garlic cv. ‘Music’. (Zandstra, 2006)

John Zandstra did some research on scape removal and the influences it has on yield.  Scapes should be removed sooner rather than later to preserve yield and bulb size (Figure 1). The longer you leave the scapes growing in the field, the more energy the plant will divert to creating a flower and bulbils - to the detriment of bulb size and yield.

Figure 2. Influence of leaf removal on yields and bulb weights of
garlic cv ‘Music’. (Zandstra, 2000)

Best practices also suggest that the scapes should be removed by hand (Figure 2).  Using a sickle bar mower, or other mechanical means to remove the scape often damages leaves.  Damage to the leaves reduces the photosynthetic potential of the plant, resulting in less energy to be poured into bulb development.  In short, even a small percentage of leaf damage will reduce bulb weight and total yield so be careful when removing scapes!

Scape removal is also a good time to be on the lookout for leek moth damage in your crop. Leek moth is a new pest to Nova Scotia and has been found in Kings and Annapolis Counties.  Cornell has an excellent site devoted to providing further leek moth information.  If you grow garlic, leeks, or onions, I strongly suggest you make yourself familiar with this pest.

Leek moth damage on garlic, photo credit Amy Ivy, Cornell

Leek moth damage on garlic leaves, photo Amy Ivy, Cornell

Leek moth damage on garlic scapes, photo Scott Lewins, UVM