Fiann Ó Nualláin says this is the prime month to decimate those unhelpful summer weeds, pests, and diseases.

IN 46 BC, the Roman emperor, Julius Caesar, reformed the old Roman calendar into the Julian calendar and renamed July after himself. 

So, in Caesar’s month, it’s a good time to go on the warpath against summer weeds, pests, and diseases.

Know your enemy. Be aware of carrot-root fly picking up the scent of carrots being thinned — he hunts by scent on the air and can cover up to five miles on a mere whiff. So, thin on a still day.

Snails and slugs are ever-present. Even if today is a scorcher, the heat only forces them underground to seek moisture, but they are still there and will return to action once nightfall cools surface temperatures. 

Booby-trap, or at least beer-trap, the garden. Night-time beer traps can be emptied onto the compost heap in the morning, dead slugs and all.

Aphids can blitzkrieg a plant in an instant. They are sap-suckers, hence the mis-forming of your vegetable foliage and the changing of its colours. 

In removing the sugary sap, they also remove the moisture and the chlorophyll that give the plant its structure and pigmentation. 

Those excess sugars are secreted out as honeydew, which draws fungal infections closer and attracts garden ants who feast on it. 

Ants even protect aphids to farm them for the honeydew. Both nymphs and adults feed on plant sap and both can transmit plant pathogenic substances, in particular viruses, from one plant to the next. 

Spraying the foliage and stems with garlic kills aphids, but leaves a bitter taste and spoils the flavour of honeydew.

One of the major culprits for GIYers in July is an invasion of potato cyst eelworm. There are two types — golden-cyst eelworm (Gobodera rostochiensis) and the white-cyst eelworm (G. pallida). 

Their cysts are yellow and white, respectively, but both turn brown with maturity. The yellow is more predominant in southern counties. Both cause the same damage and both require the same treatments.

Damage is noticeable in mid-to-late summer. Potato-cyst eelworms are tiny nematodes. 

They look eel-like under a microscope. Pregnant females adhere to roots and mature to swollen, bead-like cysts that contain 200 to 600 nematodes. 

They affect potatoes, tomatoes, and aubergines, feed on their roots and stunt growth and yields. They also spread viral diseases.

Affected plants may fail to flower and form fruits/tubers. Leaves will turn yellow, then die from the bottom of the plant upwards. 

The cysts persist in the soil for years, infecting future plantings of potato or other Solanaceae crop. The best treatment/control is crop-rotation. 

Opt for resistant varieties. Lift and destroy affected crops to avoid soil build-up.

The site should not be planted with host crops for seven years. By then, all cysts should have hatched. 

With no host to feed upon, the released nematodes will quickly die off. Meantime, repeat autumn-harrowing and deep-cultivation in winter and plant camomile, tagetes and tansy, as fallow ground-cover can diminish populations. 

Soil drenches, with bio-fumigants of neem, chilli solution and nicotiana, are organic alternatives to chemical control. Mycorrhizal fungi may also be useful.

But there are threats other than pests. The Ascochyta complex sounds like a blockbuster spy or sci-fi movie, but it just reminds us that disease manifestation and identification are not always straightforward. 

There are at least three fungi that can cause leaf and pod spots — most often Ascochyta pisi, Mycosphaerella pinodes, and Phoma medicaginis.

In collaboration or singly, the agents of pea-leaf and pea-pod spots can manifest in any month that peas are growing, but especially in holiday season (July and August), when neglect is most likely. 

This fungal infection manifests as small, sunken, circular spots, with tan to dark-brown perimeters.

Soon, additional, tiny, darker spots appear within the initial spot area — this time raised and spore-bearing. 

Spots can join to form blotches and, in damp conditions, turn infected parts black and slimy — all the hallmarks of bacterial blight.

Individually, Mycosphaerella pinodes exhibts more purplish spots; Phoma medicaginis often originates at soil level and kills roots, and Ascochyta pisi rarely attacks the basal areas of plants.

The damage results in low yield, dieback, and necrosis of the plant, with inedible pods and reduced storage capacity of harvested or salvaged peas which cannot be stored for seed. 

All can spread to beans and other legumes. The best treatment or control is good garden hygiene and spacing for airflow and drying aspect.

Homemade fungicides are effective, (½ teaspoon of bicarbonate of soda to a gallon/4-litre water-filled sprayer every 2-3 weeks). Remove infected material on sight and burn, don’t compost. Look for varieties with good resistance.

One of the biggest culprits is bindweed. I don’t mind dandelions, nettles, chickweed, cleavers — they are edible, medicinal and beneficial — but bindweed is selfish, un-giving, and ruthless in strangling whatever is in its path. 

Bindweed can refer to two, similar, trumpet-flowered climbing plants; Field bindweed (Convolvulus arvensis) and Hedge bindweed (Calystegia sepium, formerly Convolvulus sepium). Both are a pervasive weed.

Their fleshy roots spread rapidly through the soil and as deep as five metres. Slivers of root regenerate quickly. The nature of the sprawling growth and clinging stems is to smother and choke plants. The milky sap can irritate. 

Bindweed can host several viruses that affect the nightshade family (potatoes, tomatoes, aubergines and sweet and hot peppers). Both are treated in the same manner. 

Hedge bindweed is not confined to hedges, and field bindweed is at home in your fruiting hedge as much as in any cultivated field. A war of attrition is necessary. 

Bindweed are notoriously difficult to control organically, but constant hoeing and root removal (over several years) will undermine them, if they don’t undermine you, first.

The trick is to starve them out, by defoliating; severing at soil level; blocking sunlight to prevent photosynthesis, and boiling water on roots. 

Agitate them to death. Mulching is ineffective. 

Use bamboo canes to let them crawl up, away from crops and ornamentals, and spray with vinegar or other organic weedkiller. Throw a bin bag over them and let them wither. I know some of this sounds cruel, but war is war.


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