Written by: Mr. Peter Klapwijk, Green Architect and Connector with a vast growing history.

2HARVEST | www.2harvest.nl

Crop hygiene and phytosanitary control are essential for healthy crops. Read on for tips to create a sound hygiene strategy that will lead to resilient crops and optimal growth.

What is crop hygiene?

A hygienic greenhouse is one without pests, weeds, diseases, pollution, or fungi. All these issues come from the outside and get into your greenhouse from insects, contamination from your workers, or excess still water.
It is important to create a strategy to avoid issues that can hinder growth. Your strategy can include preventative methods, monitoring protocols, chemical usage, acceptable pest levels, and biological controls.

Disciplines and protocols for ensuring crop hygiene

There are several different types of methods for ensuring crop hygiene. First, there are preventative methods, second are monitoring strategies, and third are responsive protocols.

Preventative methods

There are many things you can do to prevent contamination in your greenhouse. First, you should use high-quality netting and place hygiene locks at all greenhouse entrances to prevent insects, fungi, viruses, and bacteria from entering.
Before planting any new crops, you should scan the greenhouse for weeds or any small plants on the ground. Aphids and other pests tend to gravitate toward these floor plants that may not get sprayed by your greenhouse sprayers.

Your greenhouse sprayers should be set up to reach every inch and corner of your greenhouse so you don’t miss any parts of your plants. Any parts of your plants that don’t get sprayed are susceptible to pests.

It’s also important to check around the outside of your greenhouse for any aphid nests, weeds, or anything else that could possibly migrate into your greenhouse and cause problems.

Your other most important preventative methods include protocols for your workers. Your workers should wear protective clothing in your greenhouse and switch clothing between greenhouses to avoid spreading any possible issues. Have your workers use different tools for each row and disinfect your tools regularly. It’s also important to work in the same direction every time so that there is an equal time between when your workers examine every plant.

Monitoring strategies
Bacteria and disease spread quickly. If you find them early, you might be able to manage the spreading and keep more of your plants healthy. To catch problems as early as possible, you should set up scouting and monitoring protocols to ensure every inch of your greenhouse is scanned in timely intervals.
It’s important that several members of the growing team who can recognize diseases monitor your greenhouse. Your team may choose to monitor each row on a different day and then start over once the entire greenhouse has been thoroughly scouted.
While your greenhouse manager and his growing team colleagues should be monitoring, it is also important to instruct all employees to know what to look for in your greenhouse. Your workers are close to your plants, if they know what insects are harmful, the signs of disease, or the sprouting of fungi, this can help you catch them early.

Sticky cards that attract insects are also very useful to see what type of insects and the concentration of insects in your greenhouse. If you see any aphids or disease-carrying insects on your sticky cards, you know you need to do something to take care of them.
Need sticky cards? Paskal has a product like this. Talk to our sales team

Responsive protocols
Spraying chemicals is a common way to avoid and respond to pests in your greenhouse. Chemicals are poisonous, making them effective for killing pests, however, they are also harmful to your plants. Every time you spray in your greenhouse, you disturb plant growth for about two days. Plants do not grow for at least six hours after spraying and then it takes them time to get back to their normal growth rate. That means if you spray once a week, you might lose between 5%-10% of production.

If you spray, you must consider whether spraying is helping your plants by killing pests or inhibiting growth for too long. You might decide to allow a certain level of pests in your greenhouse so as not to disturb growth. Additionally, it is important to note that insects evolve and may be able to resist chemicals. Spraying might lead to stronger pests that will require stronger chemicals to remove them.

Another method is to use biological controls and create an ecosystem that is not friendly to pests. For example, if you have white flies or aphids, you might bring in another insect that won’t damage your plants but will eat the aphids and white flies. This method has shown long-term success. It is also more sustainable, and better for consumers and supermarkets that often prefer produce with fewer chemicals. You will avoid pests without disturbing plant growth. However, you must monitor biological controls very carefully to ensure nothing is out of hand and everything is working. There is little room for error.
A third method includes fogging or misting. Using very small drips, you can create fog in your greenhouse with sprays or biological treatments. With this method, you should cover your crops so the fog does not touch them. You must make sure the chemicals are in the air long enough to be effective, but also ensure that the chemicals do not disrupt the plants.

Battling viruses with vaccines
Vaccines are a great option for creating resilient and resistant plants, however, vaccines are not available for all diseases. If you have vaccines available to you, it is smart to vaccinate plants when they are young. Plants may get sick from the vaccines, so early vaccinations allow plants to recover before they flower or create crops.

You may also find disease-resistant varieties of plants, but you should be aware that the crops of these breeds may look or taste different than what you expect.

Creating resilient plants
The best way to create resilient plants is to keep them healthy and ensure an optimal environment for growth. This includes providing them with the right nutrients and amount of water.

For example, you might provide crops with a lower nitrogen level to reduce crop sensitivity to aphids. You might also avoid allowing free water in your greenhouse, as free water allows fungi to germinate. Once fungi germinate, the spores can attack weak cells in your plants. You might also use sulfur, which is very effective against fungi and other spores.
Keeping your plants strong is the most effective way to battle viruses, fungi, and other pests. However, your plants may still get sick. When this happens, they may not photosynthesize well so it is important to create a good environment for them to recover. Keep temperatures cool and don’t allow plants to be burdened by lots of crops.

Take good care of your plants and you will be rewarded by your crops.


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