One of the reasons why I have become increasingly disillusioned with gardening in New Zealand is because of climate change, which I have explored in my previous post. The other reason why I feel so disheartened is because of the growing number of pests and diseases which were not an issue for me when I first started gardening a decade ago but are now a huge problem. They have made gardening increasingly difficult and sometimes impossible, because there are often no effective ways to deal with them. It is very difficult for me to write this blog post as it is such a depressing subject and it is very upsetting because pests and diseases have affected our edible garden adversely, but I would really like to share my findings as it is such an important issue right now. Together with climate change, it explains why produce is so expensive in New Zealand because commercial growers struggle as well as home gardeners like myself. This makes the issue of pests and diseases relevant to all New Zealanders, even people that have no interest whatsoever in gardening, because most people include fruit and veggies in their diet and I have heard a lot of people complain about how expensive they have become, especially because we have had such an awful summer. Set out below are what I think are the five main challenges to gardeners in New Zealand nowadays. Rust For me, this is mostly an issue for garlic. This actually used to be one of the easiest things to grow. I simply popped some cloves into the ground on the shortest day (21st June for us) and harvested huge balls of garlic on the longest day of the year (21st December for us). Sourcing good seed garlic wasn’t difficult nor was it expensive. There were also a lot of different varieties available. Here is a picture of our crop in 2014, which I hung out on our washing line after harvesting and washing it. I like to leave it out in the sun to cure, so that the skin thickens and it stores better. Nowadays, it has become really difficult to source seed garlic because commercial growers have also had their crop wiped out by rust. If you are lucky enough to track some down, it is really expensive and stock is very limited. Just to give you an idea of how competitive the purchasing process is, Bulbs Direct, one of New Zealand’s largest mail order bulbs suppliers sold out of Elephant garlic in just 20 minutes last year. These days, it is impossible for me to grow garlic without it succumbing to rust and when that happens, it fails to develop and ends up resembling spring onions. Over the past few years, I have trialed different sprays to combat rust, to no avail. Last year I sprayed my plants with apple cider vinegar (ACV) (1 cup of ACV to 5 litres of water), which was recommended by someone in a gardening group I belong to on Facebook. I had high hopes for a successful harvest, but the results were mixed. My Printanor garlic (the standard white variety that is available at the supermarket) amounted to nothing, but Russian Red wasn’t actually too bad. I might save some cloves for planting this year, which is a good idea since sourcing seed garlic has become so difficult. Rust has obviously had an impact on the price of garlic at the supermarket, because commercial growers have also struggled. It isn’t nearly $60 kg because of the pandemic, multiple lockdowns and rising fuel costs, although that hasn’t exactly helped. The Tomato Potato Psyllid The Tomato Potato Psyllid (TPP) is a pest which destroys many crops, including tomatoes, potatoes, tamarillos, chillies, capsicums and eggplants, which are all things I really love growing. I am very lucky that it hasn’t hit our garden yet, but it is only a matter of time. I became friends with a guy who lives on the North Shore that used to buy plants from me when I was running my nursery back in 2017. We often share seeds with each other. Two years ago, he was hit by the TPP and was devastated. He loves growing very hot and exotic chilli plants and has given me many different varieties to try growing in our garden. He thinks it’s because a friend of his that also lives on the North Shore and grows chillies was also affected and the pests travelled from his garden since it was nearby. We are in South Auckland, but it is nothing for the TPP to fly across Auckland given that the guava moth (which I will cover below) apparently comes from Australia and flew to New Zealand across the Tasman Sea. That’s what I read in an article, anyway. I always thought it accidentally got in through fruit and veggie exports from Australia even though the Ministry for Primary Industries (MPI) are incredibly strict in NZ, but it seems I was wrong and I shouldn’t make an assumption without knowing the facts. The Guava Moth Out of all five pests and diseases covered in this article, I am perhaps the most troubled by the Guava Moth, which is a pest that affects a lot of plants, even more than the TPP. The Guava Moth affects guavas (as the name suggests), feijoas (their favourite!), citrus including lemons (which they tend to go to in winter once the feijoa season has finished) and oranges, peaches and much more. The insect makes a hole on the exterior of the fruit and there is brown residue inside. Here is a picture of a feijoa affected by the guava moth, which has become a common sight in New Zealand nowadays. It is possible to make guava moth traps (basically a “lure”) yourself using a recipe that has been floating around gardening groups on Facebook, but I haven’t found it particularly effective. It is also really time consuming to make the liquid concoction, as it needs changing every fortnight because it evaporates and the guava moths end up sitting at the bottom of the trap. Because you need plastic milk bottles to make the traps, you need a lot of them, especially if you have lots of trees affected by the Guava Moth as each tree requires its own trap. Here is the recipe incase you are interested. A neighbor at our bach (holiday home) in the far north was so angry about guava moth infestations year after year that they took a chainsaw and cut down all their trees in a fit of rage one day. At that time, we hadn’t had any issues in our Auckland garden but it has been a huge problem over the past few years and I feel like doing exactly the same thing myself. Most NZers will have fond memories of eating feijoas as a child and they were incredibly easy to grow back then. They are also very easy to harvest, because the fruit falls on the ground when it is ready and you don’t have to climb up a ladder to reach it unlike a lot of other fruit trees. Fungal disease (brown spot) on passionfruit While I haven’t cut down the feijoa trees (yet), I did actually have to remove our passionfruit vine. Every year, the fruit develops these horrible brown spots on the exterior while they are green. Then the fruit shrivels prematurely before it turns purple. As with garlic, I have used different sprays over the years such as lime sulfur, liquid copper and ACV, to no avail. This is the real reason why passionfruit is so expensive at the supermarket. It is not because they are exotic or difficult to grow, despite what people may think. This never used to be an issue when I was a child. I grew up in Whangarei (back then a small town situated about 2 ½ hours north of Auckland) and we had a huge vine over one of our fences. Every year, we had a huge crop of passionfruit and they were all perfect. Gall This is a bacterial disease which affects the soil. It can be found on roses and lilies, but seems to be more of a problem on dahlia tubers at the moment. The reason for this is because of the sharp increase in imported dahlias in recent years due to “dahlia mania”. Although dahlias have been around for a very long time, they have suddenly become extremely fashionable, largely due to the influential flower farmer Erin Benzakein of Floret in Washington state and her recent book, Discovering Dahlias. This is an example of gall which was found on a dahlia tuber last year. Luckily I pot up all my tubers prior to planting them, so I managed to catch it and dispose of it before it contaminated the ground. In addition to preventing the spread of gall in the soil, I think it’s a good idea to pot up your dahlia tubers before planting them in the ground to help prevent rot, which can happen as there is usually a lot of rain in November. That was the first time I have experienced gall. At the end of every season when I lift my tubers to store them over winter, I live in fear of finding gall on them. Once it is present in the soil, it can be very difficult to eradicate.
I posted the above picture in a NZ dahlia group I belong to on Facebook, as I was unsure if it was really gall or something completely harmless. Some members put a lot of pressure on me to name and shame the supplier and variety as they were worried about their own purchases being contaminated but I refused to because I don’t think that’s very nice. Just because my tuber had gall on it, it doesn’t necessarily mean that the entire batch of that variety was bad. Furthermore, the gall developed on the tuber after it was potted up. At the time the tuber was inspected and dispatched by the supplier, it was fine and when I received the tuber, there was nothing wrong with it. Sometimes you have to stand your ground and do what you think is right, even if others disagree with you.
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