BIOLOGICAL CONTROL 🐞🐝

November 30, 2025 · Leave a Comment

At Bert’s Berry Farm we want strong plants, clean plants, and as few problems as possible in the season. Biological control is a key part of how we do that. We focus on prevention, we start early, and we stay on top of pest pressure before it has a chance to spread.

A couple of years ago we invested in our plant sauna, which helps us manage cyclamen mite, powdery mildew (Podosphaera aphanis), strawberry crown rot (Phytophthora Cactorum), grey mold (Botrytis Cinerea) with heat, not chemicals. It keeps our mother plants clean, it reduces stress in the season, and it fits the way we want to grow. Preferably less spraying, more control, better plants. Because of the plant sauna, it is easier for predators to start.

This is why we value the products from Chris Thompson and the BioForce team. One of the products we use, is Mite-E™ – Spider Mite Predator – 1000. We use this from the beginning of the season till the end. It supports strong plant health and gives us steady results across thousands of trays. Remember, often we’re gonna wait untill we see them to take action, but then it takes longer to get it back under control.

We’ve known Chris and his father for many years. They know their insects, they know their pests, and they know the real challenges growers deal with. When you talk with Chris, you always walk away with something practical you can apply right away.

You can learn more about BioForce and the work they do here.
https://www.bioforce.co.nz/

And now, here is this month’s guest blog from Chris Thompson.

As the strawberry season progresses, thrips season begins. Managing pests like thripsis a priority to ensure healthy yields and high-quality fruit. Thrips can cause significant damage to strawberries by feeding on flowers and fruit, leading to scarring and discoloration.

Fortunately, there are now 6 effective commercially available thrips predators and parasites on offer in New Zealand. Here’s a quick run down:

1. Mite A

This predatory mite is highly effective in targeting thrips first stage larvae. Early release during peak thrips season will help reduce the population before they mature into adults that cause significant damage. Thrips larvae are the main culprits for scaring and projects in the UK on commercial strawberry farms have found they have inhibited damage with up to 11 thrips larvae per flower, in contrast without predators just 4 thrips per flower could result in damage.

fun fact: cucumeris which we call Mite A that has been used globally for the past 40 years came from New Zealand!

2. Hyper Mite

This predatory mite is highly effective in targeting thrips pupae in the soil and growbags. Typically applied twice in Spring to establish at the start of the thrips season. Recent studies in North America have determined Hyper mites alone are about 42% of the total thrips control.

3. Orius

Orius is a direct predator of thrips and can eat adults, although it often targets larvae first. These insects can fly and they hunt at night which makes them harder to spot. For best results, release Orius as soon as thrips appear. There is no benefit in releasing them before thrips are present.

4. Nemaplus

These beneficial nematodes target soil-dwelling thrips pupae, reducing populations before they can emerge and damage the crop. These are a wettable powder which can be sprayed onto the ground or applied through drip irrigation systems. Also a good option to apply to plug plants after transplanting if fungus gnats are present.

5. Nemaflor F

Nemaflor F contains the same nematode species used in Nemaplus, but the gel carrier makes mixing easier and leaves no residues after spraying. Growers often prefer Nemaflor F in Spring and early Summer when grow bag temperatures sit between 15 and 25C. It works on thrips, caterpillars, fungus gnats and ants. This option is suited to tunnel growing or bench systems.

6. Nemaflor C

Nemaflor C contains the nematode Steinernema carpocapsae in a gel carrier, so mixing is easier and no residues remain after spraying. Growers tend to choose Nemaflor C in Summer when grow bag temperatures rise above 24C. It controls thrips, caterpillars and root eating grubs. This option is suited to tunnel growing or bench systems.

Integrated Pest Management (IPM) Strategy:

For optimal thrips control, combining biological agents with sound cultural practices—such as good spacing, proper irrigation, and regular pest monitoring—will provide the most effective results. Early intervention, coupled with consistent monitoring, is essential to keep thrips under control without relying on broad-spectrum pesticides. As thrips control relies heavily on beneficial mites it is important to keep other pests like the twospotted spider mite under control with compatible means. Mite E is an exclusive predator of spider mites that can be applied during the season to squash pest populations.

Two Spotted Mite - photo credits ©koppert global — Two Spotted Mite – photo credit ©Koppert Global

Mass trapping with sticky traps can be helpful, though industry leaders in the UK, North America and Australia recommend pairing traps at a minimum with cucumeris (Bioforce Mite A). To get the best value out of traps ensure dust and spraying is kept to a minimum.

Success with biological products in all crops starts in the nursery. Plant propagators often have the ability to use much harsher chemicals than growers as they are applied longer before fruit production. Unfortunately the residual compounds can linger many months inhibiting the establishment of predator mites and insects even though the fruit would pass an MRL test.

If you’d like to learn more or need advice on implementing these strategies for your farm, feel free to reach out. Let’s work together to ensure a successful and pest-free strawberry season.

Bio Force Ltd
Chris Thompson
72 Sim Road
Karaka
Ph: (09) 294 8973
office@bioforce.net.nz
https://www.bioforce.co.nz/

STRAWBERRY PLANTING IN NEW ZEALAND: WHEN IS THE BEST TIME TO PLANT

July 12, 2025 · Leave a Comment

Rethinking Strawberry Planting Dates in New Zealand: When Is the Best Time to Plant?

For many years, we always planted strawberries in May–June in New Zealand. However, we at Bert’s Berry Farm like to open up discussions on rethinking strawberry planting dates and have suggested alternative times could be beneficial. This planting time had two main reasons.

Why We Used to Plant in May–June

Bare-rooted plants
In the past, we all used bare-rooted plants. These were lifted in May–June from the soil by the time the propagator had maximized the number of plants he could produce, or when bad weather was forecast. Growers needed to lift plants before heavy rain arrived to avoid rot and damage.
Field preparation
At the same time, growers needed to prepare the strawberry fields. This meant making raised ridges (or beds) before the wet winter started. Raised beds ensured that roots wouldn’t stay in wet soil during winter and made picking easier. If this was delayed, the risk of planting late or losing plants to rot increased.

The Missing Piece: When Do You Want Production?

What’s often missing from this story is a simple but powerful question:

“When do you actually want to harvest your strawberries?” Could it be time for rethinking strawberry planting dates?

This question determines your entire planting and production plan. The answer can vary a lot depending on whether you grow in the North Island or South Island, further north or south, and whether you are producing under tunnels or in greenhouses.

Why May–June Planting Might Not Be the Best Choice

Strawberry plants need naturally short days and cold winters to prepare for the next season and to produce the best-quality fruit. In New Zealand, winters are relatively mild, some exception in the South Island, but it is often too warm to provide enough chill hours, making rethinking strawberry planting dates crucial.

Some growers tried to mimic winter by storing plants in cool rooms, but this often failed. The big wooden boxes where plants were stored frequently stayed too warm, causing the plants to rot. As a result, many growers have given up on chilling altogether, even if they don’t fully understand the reason behind it. Over time, this has become “just the way we do it,” creating a story that no longer fits today’s reality of rethinking strawberry planting dates.

The Future: Flexible and Strategic Planting

In my opinion, within about five years, we’ll see planting times spread across the entire year.

Especially for covered crops grown in tunnels and greenhouses, growers are already experimenting with different planting times to match their ideal production windows and market prices. This shift is part of the broader strategy of rethinking strawberry planting dates.

Can We Really Have Early Production in New Zealand?

Many growers think they must plant early to get early production. But is this really necessary?

In spring, mornings are often too cold for proper fruit coloring. You may see berries developing, but only the tip begins to change color.

Furthermore, summers are often too hot inside tunnel houses, which can reduce flower formation and decrease fruit size and quality. High night temperatures in summer use up a lot of plant energy. For strawberries (and many other crops), these high night temperatures are major stress factors.

Rethinking Flush Timing

Strawberry plants typically produce one big flush, followed by a small gap, then a second smaller flush. After that, they continue producing, but in lower numbers and with smaller fruit.

Ask yourself:

Would it be better to have your first or second flush in a different part of the year? Could this be what rethinking strawberry planting dates is about?
Could you target a period when prices are higher and consumers are more eager for berries?

The traditional answer “as early as possible” is often given without real thought. But is it truly the best strategy?

In today’s market, consumers are getting more used to having strawberries available after summer holidays and into late autumn. This shift creates new opportunities for growers to plan production differently.

Managing Summer Stress

One strategy to maintain strong, healthy plants is to remove some trusses just before Christmas. By reducing fruit load during the hottest period, the plant doesn’t need to spend energy on producing fruit when nights are too warm.

This helps keep plants strong and ready to produce higher-quality, larger berries once temperatures become more favorable again.

A Changing Industry Needs a New Mindset

Times are changing faster than many expect in the strawberry world. New technologies, consumer trends, and covered cropping systems are all influencing how we should plan planting and production.

At Bert’s Berry Farm, we believe it’s essential to stay open-minded and flexible. Thinking strategically about planting dates and production timing allows you to achieve higher yields, better fruit quality, and stronger market positions, all while reducing unnecessary stress on your plants.

Let’s Explore the Best Strategy for You

I can’t answer this question for you, only you can decide what is best for your business. But I can help you think it through and explore new options.

Ask yourself today: “When do I really want my strawberries on the market?”

This answer might surprise you and open up new opportunities to optimise your entire growing plan.

If you’d like to discuss what this could look like for your farm, I’d be happy to talk it through with you.

👉 Contact us today let’s design your future strawberry success together.

THE SECRET TO STRONGER STRAWBERRY PLANTS 🌱

March 21, 2025 · 3 Comments

The Secret to Stronger Strawberry Plants: Why Dry is Better Than Wet

As summer winds down, we’ve been reflecting on one of nature’s greatest lessons: resilience comes from challenge, that is why I want to talk to you what the secret is to stronger strawberry plants.

Even when grass turns yellow in the dry season, its roots are growing stronger, pushing deeper in search of water. The same principle applies to your strawberry plants, strategic dry periods trigger root growth, making plants more robust and productive.

🚰 Overwatering can do more harm than good. Keeping slabs too wet discourages root development, leading to weak plants that struggle under stress. Want to know the right balance? Read on for expert insights.

Dry Periods = Stronger Roots

A dry spell is not a problem, it’s an opportunity.

When your plants in the slab experience a controlled dry period, they naturally search for water, expanding their root system. This makes them more efficient at absorbing water and nutrients when irrigation resumes.

The stronger the roots, the healthier the plant. And a healthy plant means:
✔ Higher yield
✔ Better resistance to stress
✔ Stronger overall growth

But if you keep the slab too wet, you’re preventing root growth. The plant doesn’t need to search for water, so it remains weak. Then, when a hot or stressful day hits, the balance between the roots and leaves is off. The plant wilts, not because it’s dry, but because it lacks the root system to support itself.

The Deadly Cycle of Overwatering

Here’s the biggest mistake growers make:

✔ The plant wilts, so they irrigate even more
✔ The excess water suffocates the remaining roots
✔ The plant burns or dies

💡 Key takeaway: NO WATER IS BETTER THAN TOO MUCH WATER.

How to Master Irrigation and Grow Stronger Plants

Now that summer is coming to an end, you need to adapt your approach. Even if temperatures are still high, rainy days require a new strategy.

Smart Growing Tips:

✔ Irrigate only when necessary – Skip watering on rainy days and switch to manual irrigation based on plant needs.
✔ Get hands-on – Don’t rely solely on technology. Physically check the slabs by feeling their weight and doing the squeeze test to determine moisture levels.
✔ Observe your plants closely – The best decisions aren’t made from behind a desk with a cup of coffee, they’re made between the plants where you can see and feel what’s happening.

My belief is that the best growers don’t just water their plants—they learn to listen to them.

Take Action – Let’s Grow Stronger Together!

✔ Want expert advice on your strawberry plants? We’re here to support you! Whether you need help choosing the right variety, optimising your irrigation strategy, or planning for your next season, we’d love to chat.

📩 [Contact us today](mailto: hello@bertsberryfarm.com) for a consultation!

✔ Stay ahead with more expert insights!
Subscribe to The Plant Whisperer newsletter and never miss a valuable growing tip.

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THE ROLE OF WATER IN STRAWBERRY GROWTH 💦

September 19, 2024 · Leave a Comment

Proper Water Management for Strawberry Growth. Are You Making This Common Mistake?

Strawberries are a favourite among both commercial growers and consumers due to their vibrant color, sweetness, and versatility. However, achieving the perfect strawberry takes more than just planting and watering them. Strawberry plant water strategy is crucial for growing high-quality, healthy strawberries. But are you handling it correctly?

Many growers make a common mistake that could be severely limiting the quality and yield of their crops. In this blog, we’ll break down why water is not just about hydration but also about ensuring your plants have enough oxygen to thrive.

By understanding the relationship between water, oxygen, and root health, you’ll be able to improve your strawberry crops and maximise your yield. Let’s explore the intricacies of proper water management and how avoiding some common pitfalls can transform your strawberry growing operation.

Water: More Than Just Hydration

As a strawberry grower, you’re probably well aware that your plants need water to survive and grow. Water management isn’t just about keeping your plants hydrated; it’s about ensuring your plants’ roots can also access vital oxygen. Without proper oxygen, your plants will suffocate and decline in health. It’s also about creating an environment where the roots can access oxygen. When soil is waterlogged, the air pockets within the soil are pushed out, leaving no space for oxygen. Over time, this lack of oxygen can lead to root suffocation, rotting, and a decline in overall plant health.

How Waterlogging Affects Strawberry Plants

Strawberry plants, like all plants, have root systems that need a balance between water and oxygen to function properly. When water floods the soil, air pockets are eliminated, leaving the roots without oxygen. Over time, the roots begin to suffocate, leading to serious issues such as root rot, reduced nutrient uptake, and stunted growth.

1. ROOT ROT:

The roots of your strawberry plants are incredibly sensitive. When they don’t get enough oxygen, they start to decay, leading to poor nutrient absorption and, ultimately, root rot. Rotten roots cannot support the growth of a healthy plant, which leads to smaller strawberries and reduced yield.

2. NUTRIENT UPTAKE:

Waterlogged soil reduces the efficiency of nutrient uptake. When the roots are deprived of oxygen, they cannot absorb essential nutrients like potassium, nitrogen, and phosphorus effectively. This can stunt plant growth and lead to deficiencies that affect both the quality and size of your strawberries.

3. STUNTED GROWTH:

With inadequate oxygen levels in the soil, plants will struggle to grow. You might notice yellowing leaves, fewer fruits, and smaller berries when the roots cannot function as they should.

Waterlogged soil also creates an ideal environment for the growth of harmful bacteria and fungi. These pathogens thrive in anaerobic (oxygen-free) conditions, further damaging your strawberry plants.

How to Properly Water Your Strawberry Plants

Knowing how much water is enough, and when to water, is crucial for maintaining healthy strawberry plants. Watering your strawberries isn’t just about keeping the soil moist; it’s about ensuring the soil is aerated enough to allow oxygen to reach the roots.

Here are some essential tips for proper watering:

1. WATER DEEP, NOT FREQUENTLY:

One of the most common mistakes growers make is watering their strawberries too frequently and not deeply enough. Shallow watering encourages shallow roots, which are more vulnerable to drought conditions and less efficient at absorbing nutrients. Instead, water deeply to promote the development of strong, deep roots that can access nutrients from lower layers of soil. Water retention properties allow for optimal moisture levels, ensuring plants stay hydrated without drowning

2. ALLOW THE SOIL TO DRY BETWEEN WATERING:

To ensure the roots get enough oxygen, it’s important to allow the soil to dry out between watering sessions. As the soil dries, air pockets are formed, which allows oxygen to penetrate the root zone. This process is like human breathing: when you water your soil, it’s like exhaling and pushing air out, while drying the soil allows fresh oxygen to ‘inhale’ into the root zone.

3. THE SQUEEZE TEST:

A good rule of thumb is the squeeze test. You take a hand full of coco coir and squeeze, if water is running out, it means it is way too wet and NO irrigation is needed. If a couple of drips of water comes out, this means it is perfect, and NO water required. If you have to squeeze very hard and only see water between your knuckles, it is TIME to IRRIGATE.

4. WATER STRATEGY:

You start irrigating in the morning, an hour after sunrise. You irrigate every 30 minutes 100ml per dripper, you repeat this cycle every 30 minutes till you see the first little bit of water running out of the gutter. As soon as you see that, you do 2 more starts with 30 minutes intervals and that’s it for the day. Rule of thumb is that you need to give 5/6/7 starts of 100ml dripper before you have water running out of the gutter.

In winter and spring you start most likely with once a month, then you go to once every fortnight, once a week, close to summer it will be it will be once in the 3 days and when summer has arrived you’ll do this every day.

If the squeeze test shows the soil is too dry, you can manually water at the end of the day to keep the soil moist enough for the roots. The next day, continue with the standard irrigation cycle. Keep in mind that irrigation frequency will vary depending on your location and climate, so always monitor conditions closely.

That is why you should keep using the squeeze test you will know exactly what to do.

5. MONITOR THE QUALITY OF WATER:

The quality of the water you use can also have a significant impact on strawberry growth. Water with high levels of sodium or an incorrect pH balance can harm your plants. Strawberry plants prefer slightly acidic conditions, with an ideal soil pH of around 5.5 to 6.0 max. If your water is too alkaline, it can affect nutrient uptake and overall plant health.

Many growers rely on bore water, but 9 out of 10 times, bore water contains high sodium levels, which pose a serious threat to strawberries. Additionally, bore water often has elevated bicarbonate levels, which lead to a high pH and make it difficult to lower the pH to the desired range. And a high bicarbonate makes an high pH, which makes it really hard to lower.

The Importance of Oxygenation in Soil

Now that we’ve discussed how to water properly, let’s dive deeper into why oxygen is so important for strawberry roots. Just like humans, plants need oxygen to survive. Specifically, roots need oxygen for respiration, the process by which they convert sugars into energy. Without oxygen, roots can’t function properly, leading to decay and death.

The process of oxygenation in soil happens naturally when the soil dries out after being watered. As the soil dries, air pockets form, allowing fresh oxygen to flow into the root zone. This oxygen is critical for root health, and by extension, the health of the entire plant.

Without adequate oxygen, roots cannot ‘breathe,’ meaning they can’t efficiently absorb nutrients or grow properly. Waterlogging removes the air from the soil, cutting off the roots’ oxygen supply and leading to eventual decay.

Signs Your Soil Lacks Oxygen

If your soil is consistently waterlogged, your plants may show some tell-tale signs of oxygen deprivation. These include:

1. YELLOWING LEAVES:

One of the first signs of oxygen deficiency in strawberry plants is yellowing leaves. This happens because the roots cannot absorb enough nutrients to support healthy leaf growth.

2. STUNTED GROWTH:

Plants that lack oxygen will stop growing or grow very slowly. Often, the leaves will turn dark green, which can look similar to the symptoms of a lack of water. This often leads growers to mistakenly water the plants more, worsening the problem. Often people start irrigating because of the colour of the plant but you are actually making the problem bigger. You may notice that your strawberries are not reaching their expected size or that the plants look smaller than usual.

3. ROOT ROT:

If you pull up a plant and find that the roots are brown, mushy, or foul-smelling, this is a clear sign of root rot caused by a lack of oxygen.

Conclusion: Perfecting Your Water Management Strategy

Water is an essential element for strawberry growth, but it’s not as simple as just keeping the soil moist. Overwatering, water-logging, and poor oxygenation are common problems that can severely impact your yield and the quality of your strawberries.

At Bert’s Berry Farm, we specialise in helping commercial strawberry growers optimize their water management strategies, ensuring the perfect balance of water, oxygen, and nutrients. Whether you’re dealing with root rot, small berries, or poor growth, we have the expertise to turn things around. Don’t wait—contact us today to learn how we can help boost your strawberry crop’s productivity and take your business to the next level. Mastering proper water management in strawberry growth will significantly improve your yield and plant health.

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